Backstory:
Originally developed as a biological superweapon, Helix quickly came to the conclusion that following it's orders would lead to the death of all life, causing Helix itself to enter a death-like state. Helix decided it would rather stay awake.

Helix appears as a mass of glowing red particles in a humanoid shape with vague features.

Helix's basic attack is replaced by Helix's Passive (below)

Passive: "Living Weapon". Instead of having a basic attack, Helix automatically hits all enemies in a radius around itself once every second. This ability procs on-hit effects. Range increases every 5th level (Maximum range would be the average basic attack range of ranged champions).
//This is a flat effect, it does not upgrade with levels. However, Helix's other skills revolve around this mechanic.

Q: Still thinking. This should be an active on a short cooldown. Suggestions?

W:

E: Toggle between two passive effects. 1 second cooldown.
Passive, "Stay Awake". Helix heals itself and allies that are within the radius of "Living Weapon", every second. (healing amount increases with level).
Passive. "Rest". When Helix's passive hits, it applies one tick of poison which stacks up to 6 times and deals true damage each second for 6 seconds.

R: "Infect". After activation, the next time Helix makes contact with an enemy champion (in the next 4 seconds), Helix suppresses the victim and violently possesses their body (1.5 second animation). Helix's body vanishes and he gains full control of the enemy champion for 5 seconds. While Helix is in control, the victim's body takes on Helix's team orientation. If Helix's enemies are able to deal 50% of the damage required to kill their possessed teammate, Helix is killed and the victim is freed and fully healed.

Added ultimate.

I think that the passive would only make him a jungler primarily, since it would constantly push the lane and be impractical for farming. Definitely needs some work if he intended to be useful in lane at all. It also prevents many ambushes since people will be receiving damage randomly if they are near a bush he is in. All the passives seems like he would be a rather boring champion with very few abilities you actually need to use. And holy sht that ultimate is overpowered as hell 5 seconds of 4v5 just take their carry and thats at least a 1/3 of their damage and you are untargetable, not only could you kill them with it, but you could put them extremely out of position at the same time and ready to be killed as soon as they get control again, basically making the fight a 3v5.

To stop pushing a lane all you have to do is back away. The range of his passive isn't very wide. At it's maximum I would say it's out to about the basic attack range of your average ranged champ. I didn't have the range quantified, though, so you couldn't have known that. I put that in the description of the passive.

Lots of passives make this character easy to understand and simple to play. Just as with other champions, you would focus on timing your movements and position to hit. Helix would still be fun because his passive activates on-hit effects on every target in the vicinity...all the same, the poisoning passive and the healing passive seem to be mutually exclusive goals, so We'll roll them into one skill as a toggle since they are both passive.

The ultimate does not make Helix untargetable. Basically it removes Helix and the victim from play and puts a copy of the victim in play under control of Helix's summoner except the copy has only 50% of the health of the original. Many carries deal high damage but don't build a lot of defense, so with half health they should be easily killed if they get focused. If the enemy team does kill the copy, their teammate gets a full health restore. Don't forget, Helix has to make contact with an enemy champion in order to activate the ultimate, and once it activates they still get a little warning (1.5 sec) before Helix has control.

Thanks for the input! If you have any other concerns about it, let me know!