Syrius's reaction to Ralph and Molly becoming an Official Couple was...quite heart-rending. Poor kid...
Also, when Syrius snaps over Esmeralda's really poorly-timed insults and re-starts cutting himself in the middle of an Heroic BSOD. Molly suffering another BSOD of her own at the sight and Ralph having to literally slap the knife away from Syrius was also pretty jarring, too.
Syrius himself is a walking tearjerker. You'd think some emo teenager who crossdresses, cuts himself and speaks in such flowery language would be a joke or a cliche, but rarely are they ever done as heart-wrenchingly well as this kid.