Your voice is really good!!
But i think you could try put some inner anger, hatred and intimidation at the first two lines, since in those, XChara is trying to trigger Cross to kill XFrisk (whinch is fused with XChara) so they could find a way to defeat XGaster for good! Or at least reach close.
Whatever, at the line: "I'll take the offer then. But we must do it in secret." I think you should try to make your voice low, softier and sounding hopeful! Since in this line, XChara just explained the suffering him and XFrisk that XGaster had been putting them trough.
Getting inspired by XUndyne encounraging words and by her offer of a training that could give them a chance to finally end all this mess!
With that- I KNOW YOU CAN DO THIS BUDDY!! >:D
i didnt exactly remember which scenes the lines came from so i heavily went off of just instinct of how the line is written and such so i dont even remember the original scene haha. thank you for the insight though!!
Don't worry!! I always glad to help!! ^u^