In these last pics twigs is getting too intimate/liked by PK. You can see this in the "boys" picture as well. Pk sits right on the persian, and the persian is the only one calm and pleased, mhhhh... may it be that the marriage thing has gotten further than expected? Also, Foxy is appearing in PK pics as well, and even lexy! Well, i think for these last two to be just a case, but still... Ok, enough guessing. The pleased PK's expression is priceless.
That's because as well as being PMD-E NPCs, they also represent people, or in Twigs' case a pet, that are her friends. Much like PK represents herself whilst also being her own character. While they are the same pokemon, in this case they are representing her friends rather than the characters themselves. PK the character still doesn't like Twigs, but the real Twigs is Mel's cat.