When Blurr and Wheelie were stranded on the Jovian moon Io, Marissa rocketed from the Mars base and saved the two 'Bots from mechanical bat-missiles. When Rodimus faced an emotional crisis, Marissa tried to reach out to him - ending up in a highway battle with two Decepticons.
One of her more notable adventures was her involvement with Dirk Manus, an interstellar trader whom Faireborne and the Technobots rescued from a Terrorcon attack. Dirk was everything his name suggested: generically handsome, dashing, and sly. He was able to woo Marissa, but she stumbled upon his secret dealings with the Quintessons (who had double-crossed him by siccing the Terrorcons on him). When she discovered he still planned to sell them a powerful weapon, he tied her up and left her in the desert. Under the pretext of attacking the Quint base, he and three Technobots (who were unaware of Marissa's plight) journeyed to Saturn's moon Titan. While still in space, the Terrorcons attacked the Autobots and left them drifting helplessly. Dirk landed and sold the Quints a re-creator, which functions like a Star Trek transporter, disassembling matter and storing it somehow. Said matter can also be reassembled, with the added bonus of purifying a Transformer from damage or other defects.
At any rate, Dirk left with his payment, but in flight he discovered the chestful of money was actually something called "mimic dust." And then a Quint bomb detonated on board. And immediately after crashing, he encountered the three Technobots he had betrayed. And with them were the other two team members, who had found Marissa and brought her. Although the situation was far from comfortable, the group put off their animosities toward the trader so they could concentrate on their mutual foes. As they trekked off toward the base, Dirk used his charm to exploit Marissa's romantic weakness once again. The result was that he got intimate enought to swipe her pistol and take her hostage. When they got to the base, he offered the Bots to the Quints in exchange for his money and a way home. As a display of honesty, he used the re-creator to vaporize the Autobots. Faireborne's outrage further enhanced his image - enough that it came as a complete surprise when he rematerialized the Technobots fully healed. The Bots defeated the Terrorcons, and the EDC took the Quints' goodies.
Dirk's ship was repaired, but the EDC couldn't give him the Quints' confiscated money because of rules against rewards. So Manus simply stole the chest from the EDC vault and left the planet. However, anticipating this, Marissa had switched the real money with a box full of mimic dust. Realizing that she had finally conned him for a change, Dirk could only laugh.
On another note, there is a strong possibility that Marissa is the daughter of Dashiell Faireborne, a GI Joe officer code-named Flint. A Quintesson used a holographic impersonation of her father to capture her, and that hologram sounded a LOT like Flint. The fact that they have the same last name is probably more than a coincidence. To be fair, though, it should be stated that the GI Joe team has never been mentioned in this continuity. However, their terrorist counterpart, Cobra, has been alluded to.
One thing: The fact that Marissa's dad referred to himself as "your favorite relative" suggests either, a) her mom is dead, or b) some money could be made by a family counselor. Sure, it was a Quint hologram, but she didn't seem too surprised by his choice of words.
As an aside, Marissa's Quintesson captivity led her to be the first known human to travel through a black hole into a negative universe and back again.