Oops. I think I just rated this as 'Insightful' because I didn't know that you could only choose one of the categories (meant to chose 'Insightful' and something else). At any rate, I'm just testing the rating and reviewing system to see how this works, and decided on one of your stories because I could leave actual feedback on it without going mad with it (an archive system that encourages real feedback and, gasp, concrit! The concept is making me heady and I may end up getting blacklisted for leaving lots concrit that has 'What I disliked' as well as 'What I disliked.')
At any rate, I liked the content of this and the characterisation of both Ryoma and his perception of Momo-sempai was spot on. It has Ryoma's laziness (the desire to keep it simple), his arrogance, and his laconic style of speaking down pat. Additionally, it's quite insightful in how he sees things and phrases them (how he perceive social niceties wrt his mum, how he can definitely do better than his dad, his description of Momo-sempai's "underused brain") in a way that says you understand their relationship dynamics because everything's casually mentioned, as if it's just part of who Ryoma is, without a lot of fuss.
"It is different in the past when Karupin is the only softness and warmth he lets near." The 'is's should be 'was's because the sentence is talking about the past rather than the time of the ficlet and the present tense of the following sentence is talking about the time of the ficlet.