Sonic who has a lot of love to give.
i can never truly decide on how to characterize sonic as a boyfriend but for a moment i think it'd be the funniest fucking thing
completely shameless affection because he's so giddy about not holding back. He dials it back in public, but it's endless little snuggles, purring, and pecks when yall are alone. sometimes to genuinely display affection but other times he likes to test how much he can annoy reader with it
if reader is having a conversation as he's walking by, he will deadass walk up to them, pick them up ("Chattin' about somethin' important? No? Then gimmie."), and just continue walking. no explanation. he likes hogging your attention.
actively seeing you as a safe space to just plop one day. different in the way he may see tails as a safe space, he doesn't like tails to see the more ugly parts of him (gotta give the lil guy a hedgehog to look up to, after all.), and sometimes he'll still struggle to convey it with you but sometimes he'll just walk over, dead tired, and just kinda flop on you like a tired cat. maybe he'll drop one (1) joke about you being his charging station, and sometimes things don't need to be said.
good luck getting up in the morning, though. Sonic's an early bird, but that means he just likes spending said mornings clinging to you.