Eugene's eyes leapt up at the thought of Tycho crying, and he worried that they would revoke his prefect status if he was found making another student cry after less than fifteen minutes in the position. Panicked, he immediately presented the other boy with a handkerchief. He'd decided to carry one because Elisa's close proximity increased the chance of tears, but also because it was adorable and frilly and when he pulled it from his sleeve he felt like a muggle magician, which was such an awesome feeling he was considering pursuing it as a career. But Eugene was unlikely to make it as an entertainer if he built a reputation for making his friends sad.
He hoped Tycho wasn't upset because he hadn't got Eugene anything. Eugene had had a lot of fun painting Tycho, he had even depicted his roommate in what Eugene had presumed to be his favourite pyjamas, and had been looking forward to seeing his Tycho's reaction (before he learned that the reaction was extreme Sadness). It was very much a selfish endeavour.
"Don't cry. It's a nice present, I promise!" He gave Tycho's arm a little squeeze. "Yeah, go on, open it. I thought about carving a watermelon in your likeness but this seemed like a better idea. Keeps longer and less chance of my little brother eating it."
He grabbed two slices of frosted chocolate cake from a house elf just in case Tycho hated the painting and needed to eat his feelings and nervously watched Tycho's face for any trace of joy.