It's likely Qui-Gon Jinn would have refused to serve in the Clone Wars. Had he failed to convince the Jedi of their shortcomings, he may have considered leaving the Jedi Order, but certainly not joining their enemies. But Dooku was foolish to believe Qui-Gon would be so easily swayed by the dark side.
Would Anakin have turned to the dark side if Qui-Gon lived?
Qui-Gon Jinn is seen by many as the best of the Star Wars prequel era's Jedi, and there is evidence that he could have even stopped Anakin Skywalker from falling to the dark side of the Force.
Through his discovery of young Anakin Skywalker, Qui-Gon Jinn brought on the Jedi Order's downfall, but did he do this on purpose in Star Wars? Qui-Gon Jinn is widely considered one of the greatest Jedi Masters of his generation.
In conclusion, it would appear that Qui-Gon Jinn was in many ways acting outside of his own team, the Republic and the Jedi, possibly for the Sith. He was the only Jedi to have learnt the Sith power of Force Ghost. If he was a Sith, his position in hierarchy in relation to Sidious is unknown.
Praven was a Sith pureblood male who served the reconstituted Sith Empire as a Sith Lord and later protected the Galactic Republic as a member of the Jedi Order.
In material that is now considered Legends, Qui-Gon is even described as a Gray Jedi. Additionally, the term has also been applied to Force-sensitives who aren't affiliated with the Light or Dark side of the Force. Quite literally, these Gray Jedi don't see things in black and white, or light versus dark.
So Qui-Gon lost because Maul was physically stronger and quicker than him. Qui-Gon is skilled but not a prodigy. And he's quickly worn down by Maul in both their encounters.
Qui-Gon Jinn, who is considered a maverick Jedi Master by his colleagues, might have been able to keep Anakin on the path of the Jedi, had he not been killed by Darth Maul. Star Wars' Qui-Gon Jinn would have been the ideal mentor for the young Anakin.
Why did Dooku turn to the dark side after Qui-Gon died?
In addition, he revealed that he thought of the Jedi Council as being at least as responsible for Qui-Gon's death as the Sith who had killed him, and that it was their perceived short-sightedness and obstinacy which had truly lead him to leave the Order.
Dooku voluntarily left the light side behind and became Darth Sidious' dark side disciple, taking the secret name Darth Tyranus and leading the Separatist army.
There would still have been war had Qui-Gon defeated Darth Maul and lived, for Palpatine had already become Chancellor and his greater plans were already in motion. But it's quite possible the Sith would never have conquered the galaxy, and the Empire would never have been established.
Obi-Wan and Qui-Gon would still struggle against Maul, but Obi-Wan's exhaustion would have proved more of a hindrance than an asset. It's likely both he and Qui-Gon would have been killed had Obi-Wan spent all his energy on Force Speed.
What would have happened if Qui-Gon had trained Anakin?
Had Qui-Gon trained Anakin and kept him far from Palpatine, Anakin might have eventually died in the Clone Wars and been completely unable to fulfill any Chosen One prophecies. He could have died an honorable death, but nothing more.
Despite the similarities, Cal Kestis really isn't a Gray Jedi in Star Wars Jedi: Survivor. He still represents the Jedi Order and upholds its values. It's possible that a sequel could elaborate on Cal's character to label him a Gray Jedi definitively.
Light Sith or light-sided Sith were adherents of Sith teachings that rejected the dark side of the Force in favor of the light while retaining their devotion to the Sith as an organization.
The term “gray Jedi” in Star Wars is somewhat of a misnomer, considering that the definition refers to one who is practically non-Jedi. That being said, quite a few Jedi can be placed into this category. But Mace Windu identified as a Jedi despite his possible inclusion in the "gray" category.
Exar Kun and Ulic Qel Droma were an interesting Master/Apprentice pair who started as Jedi and then never moved to the traditional red sith lightsaber. Based on the short lightsaber you find in his tomb in Knights of the Old Republic 2, Freedon Nadd didn't use a red lightsaber.
Th very first Sith used Jedi colored protosabers before being disarmed and exiled. Exar Kun and Ulic Qel-Droma wielded Blue and Green sabers respectively. Darth Vader used his blue lightsaber until after the duel on Mustafar. Darth Caedus used his green lightsaber for quite a while too after turning to the Dark side.
Only a handful of canon Jedi have wielded purple lightsabers, but they were much more common in the old Expanded Universe. Darth Revan is a unique figure even there, however, simply because he is the only Sith Lord known to have used a purple lightsaber.
More cunning and devious than all but the most attuned Force-sensitive beings, Darth Bane could more than likely defeat Yoda in a battle of both strength and wit.
Dooku was powerful and extremely skillful with his lightsaber, to the point he easily beat Anakin and Obi-Wan. Still, Dooku was less powerful than both of his masters – Darth Sidious and Yoda. The Battle of Geonosis set Palpatine's ultimate plan in motion, and it is considered the first battle of the Clone Wars.
