WARNING! This will include spoilers with evidence through the whole series. Edit
This also includes opinions... EditPlease do not fight over who is better just simply state what you think and be done with it. Please and thank you!
Sophitz is what Sophie and Fitz are called as a team by Keefe. Sophie has had a crush on Fitz through the whole series and has second thoughts once in awhile. Fitz is the first elf Sophie had met and he's the one who showed her where she really belonged. There was only one time when they fell apart and that was in Exile when Alden's (Fitz's dad) mind became broken. Fitz is the one with the closest relationship with Sophie because they are cognates-in-training with multiple trust exercises which includes telling all of their secrets to each other. Fitz only started really showing his possible feelings for Sophie in Lodestar when he holds hands with her... a lot... but also leans in and almost kisses her but Keefe interrupts... another possible match... read below.
Keefe is always the first one to volunteer for anything that involves Sophie including a time in Neverseen when Dex makes a breathing-underwater contraption for two, and he wants to share with Sophie. (their nose would literally be touching together). Keefe also insists in being by Sophie and sometimes says things that also may seem flirtatious. He always says out loud in school multiple times, "It's a date, Foster!" sarcastically, but to show off when he comes over. He also always insists on her being more relaxed and calm. It never really says she likes him but sometimes she gets the weird heart fluttery thing and also cares a lot about Keefe. Another thing was on Neverseen when Keefe and Sophie are by the mountains in the Sanctuary when it says, "...her stomach filled with fluttering things, which flitted around even more when she noticed how close they were now standing. The toes of their boots were almost touching, and his breath felt warm on his cheeks."
Dexphie is a mix of Dex and Sophie and can possibly be a love match. Dex and Sophie have been best friends through the whole series and have a close relationship. Dex has always made cool contraptions for Sophie to keep her safe including the Sucker Puncher (gives a burst of air so then your arm goes at a faster speed punching harder.) and a panic switch (a ring with with a switch that will alert Dex to come help.). Dex was the "lucky" person and was going to see Sophie in the caves when the Neverseen came and kidnapped both of them doing horrible things like drugging and burning them. Dex always blushes with Sophie and takes any moments he can to be with her. He is always jealous with Fitz and how they always are with each other...
Note by Connie-Lionheart3: Tam and Linh are also mentioned in Neverseen, as they help when Sophie and friends go to Ravagog. In Lodestar, Tam also is mentioned several other times in relation to Biana, including when Keefe makes clear that he is the president of the Foster Fan Club and Tam says he has no problem with that and looks at Biana, blushing.