Throughout the campaign in battlefront 2 you play as Inferno squad, supposedly the most elite special forces team the empire had.

Some background:

There's a point in the game where Del, a member of the squad, meets Luke and they have to work together. During this time, Luke manages to sway Del's opinion of the Jedi, and the force in general.

The final act of the now dead Emperor shows the Empire's true colors to Inferno, as they are ordered to activate orbital laser attacks on loyal imperial civilians. Del and his CO Iden disobey these orders during an extraction mission and break away from from the Empire, betraying the 3rd squad member Hask, who chose to remain loyal. Del and Iden evacuate as many civilians as they can stealing the Raider class corvette and fleeing the system.

Eventually, and I'm skipping a good chunk of content, inferno becomes a key part of the rebellion trying to stop these orbital laser strikes on other helpless systems. Leading Del and Iden to be an active part of the events on Jakku, where the Empire is considered to have fallen. During the battle Iden confront's her father, the admiral who gave the orders to attack civilians and Hask, the 3rd member of inferno who was betrayed. Both are assumed dead by the end of the battle. It's on Jakku that it's revealed Iden and Del become romantically involved...

The main point:

The game ends decades later with Kylo Ren hunting down Del who was hiding on the planet where he had met Luke years before. All this is just before the events of TFA. Kylo is searching for the map to Skywalker. During this interaction it is revealed that he had a child with Iden and that Del was the one who gave the map to skywalker to the old man in the beginning of TFA. Kylo, satisfied with what he found exits and in enters Hask, in First Order officer attire. Hask does the usual bit about betrayal and the weakness of abandoning the life of a solider for a child. Before Hask executes Del, Del urges Hask to leave Iden be, not out of fear, as Del was chuckling at the notion and left Hask with a quote similar to "it won't go well for you".

The game ends there.

I'm putting in that Rey may be the child of Del and Iden. My reasons being:

1.) By the end of the game it's clear Del has a deep faith in the force.
2.) The elite skills Iden has could very well be attributed to untrained force sensitivity.
3.) The timing and settings add up.

3a.) If Del and Iden are Rey's parents, they'd have left Rey on Jakku right about the time Kylo betrayed the Jedi, and the First Order became a real threat. It would make sense, after experiencing the Empire's evil first hand that they'd want to hide their daughter before joining the resistance.

3b.) Del was a firm believer in the force and that luck was never the full story, so he seems the type of person that would hide his child on the planet where both the old empire fell and his relationship with the mother began.

3c.) Rey was abandoned. The fact that Del dies and Rey's parents never return strikes me as a strong coincidence. (specifically with what Maz tells Rey about belonging in TFA. Which seems awfully sure that whoever the parents were they're not coming back).

3d.) Final chapter of the game, presumably where Iden must fight Hask, isn't being released until TLJ. Which could mean the lineage is revealed there, or in the movie. Doesn't make sense to hold back the last chapter of the campaign unless there some big reveal.

4.) Rey has an Imperial accent. (has been mentioned before for other lineage guesses, but still applicable here).