What would you do. *long post lol sorry*

I went to high school with one of my trainees (let's call him L) and he barely spoke to me. He is 18, the same age as me and another coworker, M. The longest I've ever had to work alone with him was 30 minutes (and my boss would be there for 15). Today it's an hour & a half.

L has no respect for anyone, even my boss. Doesn't listen, thinks he knows everything. Always leaves shit for others to do.

At work I'm a pretty calm person, and I get along really well with all the other trainees and offer them advice and tips I've learnt. My boss said to me "anything I tell you, I want you to tell the trainees". So I do. They always listen and thank me for helping them out.

First time I spoke to L at work, he was 15 minutes late. I took him aside and said "hey, try and come 5 minutes early just because some of us have tight schedules and boss gets pissed, and if you can't, call and let him know". I was told he came 20 minutes late the next day.

He often works with D (he's around 30), and he always complains about L. Another coworker, M, is also 18. She said L gives her more respect if she's wearing makeup. She also flipped out one day and told him to lift his game since they get the same wage but he does nothing and she does everything.

In the 30 minute encounters I've had with L, I've gotten so angry with him every time, and I'm actually a calm person so it's odd.

Most of the time, I leave 5-10 mins late, so I'll be in the back getting my bag, D will be in the freezer doing defrost or stocktake (so he can't hear the alarm). I'll come out and see L washing dishes, with a line of people waiting to be served. It's absolute bullshit.

Last week, he started preparing food WITHOUT GLOVES and left the freezer door wide open.

I'm scared I'm gonna kill him lmao, what would you do?