Being around the Marauders a lot in her seventh year at Hogwarts Lily quickly learned how to tell if a Marauder was angry and what to do about it.

James was easy: if he walked away he was probably angry about something. He had grown up being told "if you have nothing nice to say don't say anything at all". Of course, this didn't apply to Snape and the other Slytherins, but this rule was applied to everyone else. If he was angry he knew he would say something he didn't mean so he took himself away. The best thing to do was just leave him alone and wait for him to come back calmer.

Remus was next easiest to notice, but a lot more difficult to help: if he was being exceptionally and cruelly sarcastic he was probably mad about something. The difficulty was finding what he was angry about. It could be anything, especially around full moon. On one occasion he had silenced the Great Hall during the Halloween feast in sixth year with a single cutting remark. He was stressed about homework and the increase in workload (unaided by him taking two more NEWTs than advised) and a first year was complaining about a vocabulary test they were due to have the following week. Ordinarily Remus would have helped the student or just ignored them. But no, one comment later and the first year was in tears, the school was silent and Remus was storming out of the hall. Normally it was easier to let him fume to himself, he had a journal that no one else knew about where he wrote down his thoughts. Sometimes he preferred to just rant to somebody - Lily often found herself hearing angry rants from him during their prefect duties together.

Sirius was more difficult: he would keep everything bottled up until he snapped. He would let himself fill with guilt and anger and sadness until he didn't know which emotion was which and it would spill out as uncontrolled rage. He had been known to break many items in such tantrums, and one time set fire to his curtains. James was the best at calming Sirius down, with Remus a close second. James was able to talk to Sirius in such a way that wasn't harsh but wasn't too gentle either. Remus however went for the more logical approach which often ended up with him getting annoyed as well.

Peter was the most difficult: if he was angry he would sulk and act like a five year old. He would refuse to co-operate so most of the time it would be easier to let him be, but he refused to be left alone. Again it was generally James who would calm him down. Peter was most likely to be frustrated with school work and by helping him with the work James could normally calm Peter down.

Lily also noticed that Remus was the easiest person to annoy. It could be anything: a classmate whose quill didn't have enough ink and created a scratching sound, someone asking for the answers, a wrapper from sweets that rustled when he was trying to work, his friends telling him to go to sleep, first years who couldn't listen to rules. And it only got worse around full moon.

James only got annoyed about quidditch so as long as quidditch was okay James was okay too. Although he rarely got angry he did get upset and offended more easily. Even so, he hid it well from everyone but Lily.

Sirius often got angry when letters came from home or when slytherins were talking about him. Anything about status and human rights could get him angry, or at least contribute. But it was small things that would set him off. Running out of jelly beans was a common issue that triggered full blown rage. It must be made clear that the lack of jelly beans was not the issue but the letters and the teasing and the pressure of others that was the real issue.

Peter's anger generally stemmed from a lack of understanding and, towards the end of year seven a sense of tiredness and annoyance that he was the least intelligent one in the group. He was loved by the group but he couldn't see it, blinded by invisible anger that not even James could help with. An anger shared by the same person he went on to help and give his own life for. An anger originating from not fitting in and wanting more power in the world.