Alexis shot herself forward with the intention to kill. She flew towards the other enemy ship that was targeting their Voyager. That ship shot fireballs towards her thinking that she could be taken out with that. They didn't want to waste their missiles on a small target.
However, that was a great mistake on their part. To Alexis, the fire was like the second source of food. She could easily absorb fire and make its power her own. When the fireballs came shooting in her direction, she deliberately stayed on the same path and got hit by the fireballs coming at a great speed.
And instead of getting holes in her body because of the attack, she absorbed the fire as if it was nothing. She could feel her energy level being boosted with each hit.
By the time the Titans of that ship realized what was happening, it was already too late. Alexis was already out of their view.
