Rose Tico is a fictional female in the Star Wars series. The character was portrayed on screen by Kelly Marie . Her allegiance / loyalty is to The Rebel Alliance. Rose Tico was first introduced in Star Wars VIII - The Last Jedi as a technician aboard the Resistance cruiser. Her job was to zap and disable anyone who was planning on leaving by using a stick to disable them. When Finn had awoken from being unconscious, he attempted to flee in an escape pod when he met Rose for the first time. Finn pretended to not be escaping but Rose wasn't having it and ended up zapping Finn.
Rose and Finn come up with the idea to stop the First Order from tracking the Resistance/Rebel Alliance through hyperspeed and take it to Poe Dameron. Poe contacts Maz Kanata who advises them to go to the casino planet of Canto Bight to find a master code breaker.
On Canto Bight, they find someone to help them but its not the person that Maz had told them to find. The person that they've recruited is just known as DJ. DJ is good to his word and gets them onboard Supreme Leader Snoke's command ship without being caught. As payment for the services, DJ requires Rose's necklace. Rose gives up the necklace but it irritates Finn more than Rose. After getting to the tracking device, DJ reveals he is working for the First Order and Captain Phasma captures them.
General Hux wants them executed by having them decapitated because Phasma thinks shooting them is too good. When Admiral Amilyn Holdo commits suicide by ramming the Resistance cruiser into Snoke's command carrier, it gives the two Resistance people a chance to escape.
On Crait, when the First Order make their move on the base, a group of Resistance fighters take to land crafts to stop the First Order. The Resistance are overwhelmed in terms of power. When Finn refuses to back down, Rose crashes her craft into Finns to knock it out of the way.
When Rose first recognises Finn, Rose thinks Finn is a hero of the Resistance which Finn doesn't believe he is. From that point on, Rose has a special romantic interest in Finn. It doesn't stop Rose from zapping Finn however.
Rose crashed her craft into Finns to knock him out of the way to save him. In saving Finn, Rose became badly injured and before she passed out, Rose confessed she was in love with Finn and kissed him. Finn was taken aback. Finn released Rose from her vehicle and took him back to the base where she was last seen recuperating. In the third film how Finn resolves the situation with both Rey and Rose is open.
Whilst on Canto Bight, Rose reveals her past. Rose had a sister, Paige who was killed as the Resistance was leaving D'Qar which the First Order was now attacking. Paige was seen trying to release the bombs that would take out the First Order dreadnought ship.
Although we don't know about the parents but we can assume things from what Rose said. Rose and Paige came from a mining planet which when the mines ran dry, the planet was no longer of use to the First Order and became a bombing range. Its probably safe to assume that the parents were killed before the Tico women joined the Resistance.