<...>
(doesn't continue to telepathically respond - whether out of wariness or courtesy towards Homura's feelings, it's hard to tell)
The first three to be discovered were Jolteon, Flareon, and Vaporeon. They all stem from Eevee being exposed to different kinds of evolutionary stones - basically, stones that can induce a Pokémon's evolution on contact.
The next two were Espeon and Umbreon. These two, they don't need any external stimuli to evolve, but all reported cases were said to only happen with Trainers they were really close to. Either way - Eevee only evolves into Espeon in the day, and Umbreon at night.
The next two were Leafeon and Glaceon. Eevee can only evolve into them when it levels up close to a special kind of rock - it's either mossy or icy. Those rocks are rare, and natural formations - but scientists have been discovering more of them as of late.
And the most recent one was Sylveon. It's not unlike Espeon and Umbreon, in that it requires a certain bond - but Eevee can only really become Sylveon if it also knows a Fairy-type move. Hence, Sylveon is a Fairy-type as well.

Outside
Um, do y-you mind if I accompanied you, meow? Two, um, heads are b-better than one.