So, after 10 years of playing DND with the same party, a buddy of mine is DMing his first adventure. So I thought I'd try something out that i haven't done before, playing 2 characters.

See, the idea that I had was to play a Bard/Rogue, but since i figured multiclassing at lvl 3 might be a bit dull decided I'd try playing siblings. Olo, a Halfling Rouge with a fascination of music and his brother Odo who was cursed to be a mimic (who can only turn into a small thing once a day) a year before meeting our new party. I talked to my bud and he said he was cool with the idea.

I've been reading up on Mimics as PCs and nothing has seemed to help. Some homebrews were cool, but it all seemed a bit overpowered.

[url=https://www.dandwiki.com/wiki/Mimic_(5e_Race)]This one was probably my favorite.[/url]

I'm not too sure about the stats though. 
how should I go about this to fairly play this character