This is based on opinion. Please don't list it on a work's trope example list.
Tear Jerker / Nack and Psycho
Whenever someone close to Nack dies or looks to be dying, he can't help but scream his Big "NO!" in terror.
In the adaption of Conker's Bad Fur Day, it's not just Berri that dies in the alternate world, but also the AU bounty hunter friends (AU Nic as well) AU Nack of that universe and Psycho had cherished being killed within the alternate world.
Batula's death in the AU world could count as well. It even made the author writing cry.
Pew the Rat's backstory on why he was the cold, bitter rat he becomes the way he was due to his being raised by his horrid captain when he was younger, the Order of Ixis, and even Lyric himself. Cruel as he may be, but he had to go through all of this and have his sight taken to gain immortality while being lied to all those years. Is it any wonder that he deserves a hug?
While Long John Silver's methods on what he does are questionable, his feelings for Swiper and even his rival Cutlass Lily are both genuine and even sweet. This makes his Heroic Sacrifice to save Swiper, once he finally breaks out of Pew's hypnosis, all the more painful and depressing.