We all know Eris' past times - cause some chaos and get multiple people either pissed off, killed or both. However, there obviously had to be some times where chaos wasn't created to the standard that she wanted. One of these incidents became the birth of a discord spirit by the name of Pip.
Sometime in Ancient Korea, there were two kingdoms who were constantly at states of war or unrest, each aspiring to marry into a more influential and powerful kingdom. This is why, when both royal couples bored beautiful daughters, Eris got to work and created a golden apple with the words "for the one who'll marry a great prince." Now if we're being honest, the apple attracted the attention of the princess' parents who fought over who's daughter the apple belonged to. In all honest, it seemed like an unforgivable war would break out due to the tension between the two kingdoms. As tensions rose to near breaking points, the beginning of Eris' plan began to take effect.
For the better half of a year, tensions rose and war broke out near three times, however to Eris, there wasn't enough chaos. To increase it, she took the golden apple from one of the princess' chambers one night and from it created a discord spirit who she didn't even name. All she did was simply tell him that his goal was to act like the high prince and play each princess on and that he should only stop once the girls got angry enough to force their parents to declare war on the other. With his order set, the discord spirit went off to work and played each of the girls on.
At first, the spirit was successful, each girl getting extremely jealous when he was with the other and there were a few incidents where they asked their parents to declare some sort of conflicted against the other kingdom. However, as time went on his deceit masquerade became weaker and weaker until both of the princesses married off into much bigger and Eris began to feel more and more angry towards the spirit. In her rage, she concealed him within his golden apple and kept it close to her, not letting him see daylight for the next 1900 or so years.
Now 2015 was arriving and the small part of Eris' heart that actually cared started to feel bad for the spirit and eventually brought him back into spirit form. In all honesty, she was a bit shocked when she saw that the spirit was forgiving of her and developed somewhat of a fondness, going as far as to ask Athena and Mnemosyne to give him enough intelligence to make him as smart as roughly a seven-year-old. Eris then sent the spirit to camp where he eventually gave himself the name of Pip.