Different games use different systems - and they help. In Apocalypse World there's a section of character creation and mechanics called Hx/History. Each of the character classes has a different one - so one is:
Everyone introduces their characters by name, look and outlook. Take your turn.
List the other characters’ names.
Go around again for Hx. On your turn, ask the other players which of their characters you can trust.
• For the characters you can trust, write Hx-1.
• For the characters you can’t trust, write Hx+3.
You are indifferent to what is safe, and drawn to what is not.
On the others’ turns, answer their questions as you like.
Another one has the following:
Everyone introduces their characters by name, look and outlook. Take your turn.
List the other characters’ names.
Go around again for Hx. On your turn, ask either or both:
• Which one of you has been with me since before? For that character, write Hx+2.
• Which one of you has betrayed or stolen from me? For that character, write Hx+3.
For everyone else, write Hx+1. It’s in your interests to know everyone’s business.
On the others’ turns, answer their questions as you like.
Each of the classes represents that character's role in and approach to the world and it works wonders for getting the party on the same page early.
In Blades in the Dark you are a team of criminals working on a heist - and you don't just each have a character sheet, but you have a combined crew character sheet that represents what type of criminal organisation you are. Whether it's assassins, smugglers, a cult, or more. And you don't just have individual XP but also crew XP, and the crew cohesion and network levels up in the same way the PCs do. Your crew has contacts and hangers on - and you can also get special abilities for the crew based on their rep and cohesion, like smugglers getting upgraded vehicles or assassins getting rituals to make disposal of the bodies easier.