I can't help myself. I can't imagine Remus Lupin as Badboy casanova and I can't imagine him just like grandad.
i think he is both and nothing of it at the same time.
He is the mastermind behind the marauders pranks.
He is some sort of self destrsuctive, like forgetting to eat or not getting enough sleep.
With his lycantrophy goes some sort of depression and a lot of physical and emotional pain.
Not Remus was the mother hen of the marauders, but James who especially fussed about Remus after full moons.
He had grown over the years, his friendship to the marauders, the girls, some ravenclaws and hufflepuffs and even some of the slytherins, pushed his self esteem.
He knows, because of his loving parents how healthy relationships work and I believe that he has to give Sirius steadiness and safety when they first started dating, because Sirius never really had a rolemodel for a healthy lasting relationship.
Sometimes he is the one that talks some sense in the marauders and sometimes he has the ideas to let their pranks go through the roof.
He likes to read, because books were his portals to the world when he was little, but also likes to spent time with the people he cares about. A win win is when he can spent time with Reegulus and Lily talking about books oder reading toghether.
So on the one hand he is really vulnerable and relies on his friends and boyfriends and on the other hand he is very confindent and stable and some sort of glue for his friends and spot of safety for his boyfriend.