I started Ashbury's "kill damn pigs" quest, and magnus got upset ¬¬, his reactions dropped a little. I had to tell him to wait far from there and finish the quest. I've read something about "bribing" NPCs, how does this work?
When a follower's reaction drops to 20 or below, a new dialog option will appear, letting you ask the follower why they are upset with you, and then you can either find the gift they ask for (usually something from a general store, e.g. dwarven snuff for Magnus, the Earl Grey tea for Gar, etc) or pass a high CH check to get the same reaction boost (+20) without the gift. Additionally, you can just use a fate point to boost any NPC's reaction (not just a follower).
Well, animals can't really be good or evil, but the pigs are considered innocent in this case. This problem was actually brought up a few times during the development of the UAP and I decided not to change the pigs' alignment, since I believe this outcome was desired by the developers.
There should be another way to finish the quest without having to kill them, like giving them something to eat. Are Follower's reactions important if they are 21+?
I don't have much experience in handling followers, but tell me, why do you have Magnus, even though he has spoken dialogues and even good ones, but he is rather weak, I prefer to have someone like Sogg, or that girl in Blackroot which uses healing salves on the team.
By character, Magnus is one of the most annoying and pathetic followers ever created, but I wouldn't call him weak. He is an exceptional warrior, by far the greatest melee fighter among those Arcanum followers who do not concentrate all of their progress on combat, while being a fairly useful technologist as well. While him having a voice actor can be considered both his upside and his downside, he does have quite some dialogue lines triggered here and there, always has something to say about the location you're in and has a rather fair portion of plot just waiting to be revealed during the game. Those factors considered, he is the most developed follower right after Virgil. All of that makes you feel like you're actually travelling with a living being with opinions, feelings and a defined character, someone with which you probably have something to talk about while travelling by train or eating lunch. Someone like that adds much more to the gaming experience than a silent, bland, emotionless and opinionless operator of whatever weapon you give him.