The two are the fastest on foot, and the best scouts that are on the Axalon. When she was first activated, she kissed Cheetor on the lips, but only in order to translate from Japanese to English. Foxfire seems to have a crush on Cheetor. Probably due to the fact that he saved her life. The two are rather capable fighters that work well together, despite the fact that Cheetor didn't receive any training in Cyber-Jutsu. She continuously gets jealous whenever Shadow Panther kisses him right in front of her which shows that Foxfire has strong feelings for Cheetor and develop a strong rivalry with her. In the Cruise Control chapter, the two Maximals are then drawn to one another, to the point where this time, they truly kiss and became an official couple.
Foxfire and Wind-Rider knew each other since they had come off the Assembly Line. Both strays and in a world that was more on politics than on the needs of others, these two were stuck together like glue, officially making themselves sisters rather than friends. But while they reformatted in life, both were troublemakers on the streets; Foxfire on land, Wind-Rider in air. Even once they were taken in by Yoketron, the two strived to help out one another, but mostly Wind-Rider, seeing as how Foxfire was born for this, Wind-Rider accelled in it like training for a job.
The two are a dynamic duo in Cyber-Ninjitsu, as they are feared both as the Red Star, and the White Comet, by the other students. Even after their Master's death, the two continued to stay together, once they signed on as Land and Air scouts for the Axalon. Even on Earth, during the Beast Wars, the two continue their bond, either in Beast, Robot, or Human mode.
Although, Wind-Rider can be a bit... overprotective. Much to Foxfire's embarrassment. Once the Crane Maximal had learned that her 'sister' had started a relationship with Cheetor, the first thing she had done was drew her katana at Cheetor's neck, and rather demonically threatened him with a sadistic smile, that if he did anything to hurt her emotionally, she would slash every part of him into tin foil.
Foxfire treated Jackfoot like a little sister.
Whereas Justin and Cheetor are the first males of either world to become friends, Aelita and Foxfire are the first females of either worlds as well. Foxfire is Aelita's guardian, as well as confidante. The two are good friends, and almost just like sisters. In fact, Foxfire helps Aelita to push forward to becoming more than friends with Justin.
Foxfire had develop an intense rivalry with her since she was the one who stole a kiss from Cheetor in Canada. However, the two seem to have a deep respect for one another, even though Shadow Panther keeps pushing it with her. And Foxfire admits that she is equally impressed with Shadow Panther's battle style, even if she isn't a Cyber-Ninja. And one thing is clear to both: both are deeply in love with Cheetor.
Of all the Predacons, Foxfire had a personal feud with Lockdown due to him killing her master and taking her Kunai while crushing her pride.
When Stinger first met Foxfire when he personate Cheetor, he was attracted to her and develop a crush on her. The feeling doesn't appear to be mutual, because she only loves Cheetor which triggers Stinger's jealousy of him.