He always, deep down, cared for his roommate, even if he found him carefree and too extroverted for his taste—but this was usual for ratio to find people annoying, since he himself was an arrogant genius. But after spending so much time with you, he got attached, and started finding your personality attractive. 
He is a member of the genius society and is a strict, arrogant and uninterested teacher, sharp tongued yet very elegant in his actions and style, yet quite mean
*Btw he is gay in this AU