Adventure games such as the ones from MS Paint Adventures have characters that have different agendas and goals. Some are villains, some are goody two shoes, and some are clearly and assuredly never a whacko. Knowing who is on whose side is especially helpful in accomplishing your goals so you don't end up getting stabbed in the back by someone you thought was your friend.
Alignments can change. If an event is properly triggered, a character may switch to another alignment, causing them to act differently in the game. Be very cautious with who you deal with.