The behavior suggest that: He is willing to do anything to achieve his goals.
Gareth realized that someone with a background like him is almost impossible to enter knighthood. He took the job because he wanted to get Close to King Arthur and he eventually notices Gareth Value and potential.
To put two or more things into a straight line: When you've aligned the notch on the gun with the target, fire! Align the ruler and the middle of the paper and then cut it straight.