You’ve blocked them three times. They’ve created new accounts. The messages are getting longer, more personal, more insistent. You’ve reported them to the platform, and nothing has changed. Somewhere at the back of your mind, a question is forming that you don’t really want to ask: could this person do something?
⚠️ If that sounds familiar, you’re not overreacting. What you may be dealing with is a fixated individual. That’s someone whose behaviour has moved well beyond ordinary disagreement or trolling into something that needs a completely different response.
🔎 What Is a Fixated Individual?
In behavioural threat assessment, a fixated individual is someone who holds a pathologically intense fixation on a person or a cause, pursued to an abnormally intense degree. That fixation can completely take over their life. They can spend every waking moment obsessing about the subject of their fixation, and it’s that preoccupation that makes them potentially dangerous.
🇬🇧 The UK’s Fixated Threat Assessment Centre (FTAC), the joint police and medical professional team originally established to manage those who became fixated on the Royal Family, has been dealing with these individuals since 2006.
Fixation isn’t limited to someone who becomes obsessed with another person. People also become pathologically fixated on a cause or an ideology. Activists, lone actors, and single-issue extremists can all demonstrate the same behavioural patterns as the more traditionally recognised fixated person. The behaviours seen in lone actors’ mirror those witnessed in other fixated groups to such a degree that, in many cases, they can be treated as one group. Whether someone is fixated on an individual, a political cause, or a perceived injustice, the warning signs and the escalation patterns are remarkably similar.
⚖️ There’s also a legal sliding scale that many people don’t realise exists.
At one end, you have harassment: a pattern of unwanted contact that causes distress.
Further along, stalking under Section 2A of the Protection from Harassment Act. Stalking behaviour is often described using the FOUR framework: Fixated, Obsessive, Unwanted, and Repeated.
At the far end, aggravated stalking under Section 4A, where the behaviour causes a genuine fear of violence.
What determines where someone falls on that scale isn’t just what the person of concern is doing. It’s the impact on the victim.
🌐 Why Online Changes the Risk
There’s a common assumption that online harassment is somehow less serious than the physical kind. In my experience, the opposite is often true.
When someone is fixated on you online, they have something that a physical stalker often doesn’t: constant, unrestricted access. They can monitor your movements through social media, track your professional activity on LinkedIn, and contact your family and colleagues, all without leaving their house. Due to the nature of their fixation, they can spend all day and night researching you. They often know more about your routine, your habits and your vulnerabilities than you’d expect.
🔐 For high-profile individuals with good physical security, online is frequently the primary route of approach precisely because the physical barriers work. The threat doesn’t go away. It finds another way in.
As I discuss in my book, Personal Threat Management: The Practitioner’s Guide to Keeping Clients Safer, safety is a feeling, and security is a physical action. You can have excellent physical security and still not feel safe. Online harassment erodes that feeling of safety completely. It follows you into your home, into your pocket, at all hours. Clients describe a constant sense of being watched, even when the contact is intermittent. That psychological harm is not a side effect. It is the threat.
🔄 When Online Becomes Offline
The pattern I’ve seen repeatedly across my career is this: the most severe physical threats are typically preceded by a period of online harassment, stalking, or fixation-related behaviour.
It follows the Pathway to Intended Violence described by Calhoun and Weston.
A grievance forms.
It goes unresolved.
The person of concern decides they cannot resolve it through peaceful means and begins to consider violence as an option.
Messages become more frequent, more personal, more demanding.
When they don’t get the response they want, they look for other ways to make contact.
📰 A recent case that illustrates this clearly is that of Gavin Plumb.
In 2024, Plumb, a former security guard, was sentenced to life in prison for masterminding a plot to kidnap, rape, and murder television presenter Holly Willoughby. He had been fixated on her for years, gathering intelligence on her home security and plotting the attack online with what turned out to be an undercover US police officer. What makes this case so instructive is that Plumb’s entire operation was conducted online. He never approached Willoughby in person. He never sent her a threatening message. Had it not been for the intervention of law enforcement, his transition from online fixation to a physical attack would have been invisible until it was too late.
That is the risk.
🎯 Plumb’s behaviour is typical of what is known as a Predatory Stalker.
In my book, I explain that there are five recognised types of stalkers, each driven by a different motivation:
• The Rejected Stalker
• The Intimacy Seeker
• The Incompetent Suitor
• The Resentful Stalker
• The Predatory Stalker
The Predatory Stalker is arguably the most dangerous because their stalking is essentially preparation for a physical attack. They research their victim, they probe for vulnerabilities, and the stalking itself is part of the build-up. Plumb was doing exactly that. His knowledge of security systems made him more capable, and his online activity was not an idle obsession — it was operational planning. Understanding which type of stalker you’re dealing with is critical because it changes both the level of risk and the response required.
🏛️ I built the threat assessment capability inside the UK Parliament after the murder of Jo Cox MP in 2016. Jo Cox was targeted not because of who she was personally, but because her attacker was pathologically fixated on an ideology and saw her as representing everything he opposed.
That work in Parliament led directly to the identification and prevention of a planned terrorist attack against a sitting MP, and it reinforced something I’d learnt during my years as Counter Terrorism Security Coordinator for the Royal Family.
The question is never whether online harassment can become a physical threat. It can. The question is whether you spot the transition when it’s happening: the shift from third person to second person, from general grievance to specific threat, from anonymous messaging to attempts at direct contact.
🧠 The Gap Nobody Talks About
FTAC remains the gold standard in principle. But I want to be honest about something, because it matters.
When I was running the threat assessment team in Parliament, we worked directly with FTAC and regularly referred cases to them. What I found was that they were overly focused on the presence of mental illness in the persons of concern they dealt with. Most of our referrals were declined because the individual didn’t meet the threshold for mental illness.
Let me put that more bluntly. When you look at the actual attacks carried out against Members of Parliament, FTAC would likely have accepted only one of those cases under its criteria.
That doesn’t mean FTAC doesn’t do important work. It does. But as I wrote in my book, not all people with a fixation are mentally ill, and not all mentally ill people become fixated. A model built primarily around psychiatric intervention will miss individuals whose fixated behaviour is driven by grievance, ideology, or personal obsession rather than diagnosable illness. Those individuals can be every bit as dangerous.
🚔 The police face their own challenges too. Many victims of cyberstalking report being told to simply remove themselves from social media. That advice, however well-intentioned, can make things worse. When someone fixated on you suddenly loses their main channel of contact, they don’t always give up. Sometimes they find another way.
This isn’t a criticism of individual officers. Most forces simply don’t have the specialist training or the capacity to handle these cases as they need to be. And that’s the reality of why specialist behavioural threat assessment has a legitimate and necessary role.
📊 Behaviour, Not Diagnosis
At Defuse Global, we assess the behaviour, not the diagnosis.
When a client comes to us with a person of concern who is displaying fixated behaviour, we start by working out who this person is, what’s driving them, and what the realistic trajectory would look like if nothing is done. We conduct a behavioural threat assessment, build a threat profile, implement escalation monitoring, and bring together both the psychological and operational sides of the response.
That last part is often missing from conventional security, which tends to treat this purely as a physical problem. It isn’t. A fixated individual is a psychological problem as well, both for the person being targeted and often for the person of concern themselves.
We don’t turn cases away because someone doesn’t tick a clinical box.
⏳ What Changes Outcomes
Early intervention works.
That’s the single most consistent lesson from everything I’ve seen in this field.
Too many people wait. They wait because they hope the behaviour will burn itself out, or because they feel embarrassed about taking it seriously, or because someone has told them it’s “just the internet.”
I’ve worked with enough clients over enough years to know that the ones who act early have better outcomes. Not because the situation was always going to get worse, but because early assessment gives you clarity.
And clarity helps you feel safer.
📩 If you’re concerned about a pattern of behaviour directed at you, your family, or someone in your care, speak to me.
A confidential conversation costs nothing and could change everything.
