These characters are incredibly nice... the nicest you will ever see.
They love people with a deep, spiritual love that means they will shake heaven and earth, destroy gods and planets, bring nations to their knees, etc. They will believe the best of everyone and always give someone second chances (though they will defeat the villain). They're not forgiving of harm done to others and they are extremely dangerous often when pushed too far. They are the ones who will suffer for the sins of their loved ones. Most people think they're insane, but somehow they pull it off.
These characters are the ones you can always trust. They are heavily idealstic but a few are cynical. One of the greatest examples of this is Optimus Prime who does not want anyone to be harmed. He believes anyone, even Megatron, should get a 2nd chance.
Finn (while a bit nuts at times and wants Magic Man dead) can get along with anyone who isn't completely evil and his DNA is implied to be pure in his "son." Stormo who is much like him. He also puts up greaty with the ocassional moral ambiguity of Bender, Heloise, Skipper and King Julian display and will kick anyone's ass who threatens his friends. Finn is very helpful and trusting to all even The Ice King despite everything between them in the past.
Lizbeth (while very studious and a loner) is very nice to her friends, is not out for any reward to her hero work just to help others, and gives her foes a 2nd chance to change, such as Slade, Darkwarrior Duck and others, but this nice nature doesn't mean she's Harmless at all and she won;t hesistate to defeat any villain that harms others she cares about, she refuses to take a person's life away even if it's a mercy kill . And she never gives up when focused on her duties to protect, Hunson Abadeer (Marceline's Dad) found this out the hard way.