Eva and Carmen would be about the same age, about 26-27, Danni would be younger about 22-23. Eva is from Brazil, is outgoing and is a world -traveller, a risk-taker, and seems to have a lot of money. She never frowns and is never surprised by anything. She may also have a case of ADD. Though she might make Danni do some crazy things, she actually is never mean-spirited, she just likes her fun out on the edge of reason.
Carmen is cautious, suspicious, and protective of Eva. She had a major crush on Danni a few years before, and is dismayed by his sudden cross-dressing and his break-and enter into Eva's room. She is wealthy as well, but more a New-Yorker, prone to outbursts and can fight like a guy when she wants to.
Eva and Carmen never hide their thoughts, they always say what they are thinking at the moment.
Danni, for some reason, is Eva's room-mate. Ah, well. Suffice it to say, Danni never moved in Eva's circle, so they are not much more than friendly acquaintances prior to Danni's break-in to wear Eva's clothes.
Danni is quiet, perhaps intellectual, and semi-athletic. He is also not as mature as the girls: he is easily shocked, shy, judgemental of others, easily led, and pouts and sulks several times during the story. Cross-dressing is something that he's experimenting with sexually, but it also has to do with his worship and fascination with Eva, whom he loves with all his heart. Along the way to her heart, though, he finds he has an almost magical way of becoming female when wearing women's clothes. Eva pushes him further and further with each new episode.
Some episodes, like those of Danni's Dreams (Pony, Prison, etc), are fantasy. They occur as Danni takes hormones, has libido problems, gets implants, etc. Eva always helps Danni in the morning after by finding an acceptable (most of the time) outlet for the frustration. Readers can suggest their own fantasies for these episodes.
But others are the real deal, and are planned out.
Danni transforms, physically and emotionally, and ends up losing himself in the role, and becomes more than what he was before. He also catches Eva's attention, at least for a few short sweet years.