So the character I portrayed Eniac had a few contradictions so I am going to amend his characteristics. I am also going to introduce how the two develope together and the underlying plot of the story.
I need Eniac to be new to the pony environment, the easiest way is to have him come into the town this is set in as a stranger, an outsider. This gives Sugar Plum the incentive to find out more about the new pony in town. Now without going into backstory Eniac will start of quite cold and belittling to Sugar, shutting down comments and not giving her any attention. This, however, is a mask that Eniac has put on due to hurt he has received from the place he has come from.
In truth he is the wide eyed, curious person mainly mentioned in the first iteration of Eniac. This is still there deep down, but because of his love of the world he can easily be hurt resulting in his sour character at the start, so he keeps a journal of discoveries and tinkers in his home. He is closer to himself here in his haven, of course after he has started to settle. Now all I need is to get Sugar to see him like this.
There will be a point where Sugar gives up on Eniac and stops trying to interact. It's at this point that Eniac can start to break his fear of connecting with someone. Noone else is interacting with him because of his cruelish nature so when Sugar Plum stops coming he is left alone. Here he actually goes to seek out Sugar with some excuse. Also allows for a bit more bonding as Sugar would see through the fake reason Eniac has given.
Here Sugar Plum is slowly introduced to the real Eniac allowing Eniac to develope to the excitable pony he really is. But now we get to the point we're Eniac becomes super focused on his curiousity ignoring Sugar as he can now interact with other ponies and the world. Ending up to a situation where both end up hurt, Sugar because she has been rejected and Eniac because his lack of judgement pushes ponies away, this allows for the final realisation for Eniac (to be friends with someone you have to put in effort) and the realisation of Sugar (to be more understanding that not everyone will give you attention the whole time).
It plays more like real life the two have these flaws which they slowly fix without realising. This reinstates the flaws in some way as the don't realise what they have fixed. But now they can see how they developed and realise how much they needed each other in this process. This is not a romantic novel, I aim to have Eniac and Sugar as close friends at the end. I think this still follows the story arc of a problem, tension, climax, release and then resolve.
Again leaving it late but I think it is all coming together now. What does anybody reading this think?