Ariel is not much of a fighter - he sings in the Heavenly choir instead, and he's pretty good at it. That, and his obedience make him a really good little angel.

Sometimes he wishes he could leave though. He's terrified of making mistakes or to express his true feelings to the point when he simply loses his voice once he'd try to speak about his deeper emotions. He's generally very pleasant, polite to the point of formality (took him a while to call Aziraphale by his name instead of addressing him as 'Principality') and has an immense passion for music as well as a natural angelic aptitude: he can sing any song after hearing it once perfectly.

He goes well with Aziraphale or other angels but of course demons aren't banned from trying to interact with him.

He might also leave the fandom and become a human or aasimar, we just need to find him a reason why he's so terrified of authority.