...Plots...
Help...? Kerberos will run into many soquili that need his help and he will do whatever he can to help. Whether it be him fighting off a monster or helping a mare make a stallion jealous. These will often be in exchange for something Kerberos wants (ingredients for his potions, assistance with a task, or something else he finds interesting)
Haunted? I can help... Kerberos follows a soquili around for a while, but stays hidden in the shadows. He makes the soquili believe that they are being haunted by a creature and when he happens to run into the soquili one day, he offers his help.
Illness and Cures... Kerberos makes a soquili ill. When he runs into the soquili, he offers his healing abilities to help the soquili out.
Beauty and the Beast... Eventually, I would like for Kerberos to settle down with a mare that can see past the wall he has put up. She helps bring out his soft side. He would be very possessive of this mare.
Training... Kerberos helps with training a young soquili to fight or make potions. This soquili and Kerberos have a strange friendship where they respect each other, but hate each other at the same time.
Wishing Star... Kerberos meets a mare (or maybe stalion?) that he helps with a great task. This soquili sneaks away before he can get his payment, so Kerberos goes to the wishing star in hopes that it will give him what the soquili owes him. What Kerberos gets instead is something he didn't sign up for. This will eventually lead to more plots between Kerb and the other soquili.
Along with this plot, I need someone that is willing to sort of trick Kerb into believing that the wishing star is something that will give him whatever he wishes for, rather than what it will really give him.
Enemies... The stallion's main goal in making deals is to always come out on top. He wants what is best for him and doesn't care who he has to step on to get to the top. Kerb makes a deal with a soquili and ends up screwing the soquili over with a bad deal. The two become enemies after this point.