Commander Charles 'Trip' Tucker III

Since Terra Prime:

It took Trip a little while to get over the death of his sister and baby Elizabeth, he has even learned to deal with some of his feeling for T'pol.

He agreed to take the engineering assignment for the 3 new NX ships because he knew that he would still be able to see T'pol since Enterprise had been back and forth to Earth so much recently. Of course, things don't always go as planned when Starfleet sends the Enterprise on deep exploration and what he thought would only be months turned into a whole year.

Season Five:

When Starfleet decides to upgrade the engines on the Enterprise and Columbia to the same warp capacity the new ships were getting, Trip emphatically asks Admiral Gardner to oversee it. This way he will get to spend some much desired time with T’Pol as he will be working on the Enterprise. In the first two episodes the Enterprise has to deal with a Romulan attack and during this attack the Enterprise will be hit hard resulting in the death of the Chief Engineer who replaced Trip.

At the end of the second episode, Trip knows that the 3 new ships will need to be completed soon and feels obligated to help get this done. T'Pol however (prompted by her dreams and feelings) practically begs Trip to stay since they now need a new chief engineer, and most importantly - T'pol says she needs him. Archer also believes that Trip should remain on the Enterprise so Trip agrees to stay. When they return to Earth Archer is able to convince Admiral Gardner to let Trip to remain on Enterprise.

Also during season five the new nurse Angela Vanson, will become somewhat infatuated with Commander Tucker. She can't understand why such a 'hot' guy would go for someone like T'Pol. This will be explored though season five as Nurse Vanson tries to find ways to impress the Commander. T'Pol will notice her efforts, and although lacking in emotion, we can see that she is a little concerned.

Commander Tucker will have a lot to do in this season that will seem him in jeopardy quite a bit.

TnT Notes
The focus on Tnt will be roughly the same as season 4, we are not turning this into a soap opera but at the same time the TnT story is a part of Enterprise.

TnT will intentionally keep their relationship low key not just because most of the main crew know about their relationship, but for professional and political reasons as well.

(So maybe the holodeck in TNG is not accurate on every historical fact especially relationships! Do you document your relationships?)