I can recall with aching clarity the first time I realised that a relationship I had established with a child was in trouble. It shook me, and not because the low point was when Lucas ran across the car park screaming that he was going to punch me in the head (which he then proceeded to do) but because I had always prided myself on making serious headway with children who found school a difficult place to be successful.

One of the fundamental attributes of any good teacher is the ability to get on with and, frankly, to like young people of all varieties. When we come face-to-face with a new class, we make it a priority to show all the children that we are stable, reliable adults worthy of their trust. We do this, and more, in order to establish the classroom as a safe space for children to learn, and to coexist with us and their peers. We then ensure that we build on this as the days, weeks and months pass by.

It is this groundwork that pays off if there are problems with our relationships later on. But, as I learned from my experiences with Lucas, it takes more than good foundations to fix a broken relationship.

So, what else did repairing my relationship with Lucas teach me?

First, when things go wrong in a relationship with a pupil, you, as the teacher, will probably be the one who initially has to do most of the running. If you’re determined to sit it out until the child makes the first move, you’ll be in for a long wait.

However, things will get better more quickly if you involve colleagues who can support you along the way. With Lucas, it took a sustained effort to help him to overcome and manage his very powerful feelings of shame and anger. One of my colleagues in particular worked really well with Lucas, so it made perfect sense to recruit him to help Lucas feel more settled.

Second, it is important to realise that, although it might not feel like it at the time, the relationship is probably not completely broken. It might be tarnished or damaged, but - except in the most extreme cases - relationships are not built or destroyed by one-off events. This is where emotional investment comes in.

The school that Lucas attended was one for children with behavioural difficulties. Working there, I came to understand more about how emotional investment manifests itself and this consequently helped me to change my thinking about behaviour. I could see that some of the children felt that they had very little to lose: their responses to difficulties and conflict reflected that.

They had experienced rejection on an industrial scale and had a finely tuned system of self-protection. Why wait for the - as they saw it - inevitable rejection that was to come? It was far better and safer to sabotage a relationship at a time of their own choosing.

But for those who had built up trust and a feeling of safety, and who had started to see themselves as people who could be successful in school, it was easier to overcome difficulties if and when they occurred.

I learned that the first time a child re-enters your class after a situation is crucial. They will be looking for reassurance from you, so your first words, your first gestures, your first requests or demands and your initial body language all matter. They may front it out with some bravado, such as refusing to come into your lesson or proclaiming that they “don’t give a shit”, but inside they are nervous. Hopefully, you can see this for what it is: avoiding failure and protecting themselves from rejection.

Definitely don’t compound this behaviour with reminders of past problems in the form of a veiled threat. I’m sorry to say that when I was a newly qualified teacher, I once said to a child: “Yesterday was a nightmare. I don’t want any more of that funny business in my lesson this morning.” What a welcome.

I have found using success reminders to be a helpful way back in, too. Doing more of what’s worked in the past can be a good method of refocusing. Concentrate on the big “white square”, not the “black dot”, as behaviour expert Bill Rogers would say.

Finally, remember there is a chance that we, the adults, have erred. I regret that I have escalated situations in the past and - although not all teachers will agree with me - I believe that we need to be grown-up about such things and show contrition. That’s the real key to getting things back on track with pupils like Lucas.

Jarlath O’Brien works in special education in London and is the author of Better Behaviour: a guide for teachers