Serpent's Abyss summary:

Jaehyun, an ordinary college student, has recently suffered from an unpleasant dream, and in every dream a 'red snake' always appears. One day, Jaehyun, who was heading to his own room, eventually faints on the street and receives help from Suyeon, a senior who's not close to him. From that day on, Suyeon actively approaches him, wanting to become closer with Jaehyun... Even though Jaehyun doesn't want to get involved with Suyeon, Jae-hyun can't push him away...