1. he was such a loner, especially after sirius left

2. he hung out with narcissa a lot because they were close in age, but they drifted apart when she became popular in school

3. he looked up to the older slytherins and followed in the footsteps of some by becoming a death eater

4. he taught himself to do the patronus charm while he was still in school (he was very intellectual you see) and he tried to warn sirius of lord voldemort’s plans with the horcruxes/etc but he couldn’t muster up a patronus charm after a few years as a death eaters

5. depression slowly ate at him, but he was resolved to fixing his wrongs and even though he died a depressed man, he was accepting of the things he’d done in his life and hoped for the best after he died