We thought it would be cool to imbue the new Lerk with a wildness or craziness, which we thought would fit with his sudden movements and fast changes in direction (we rejected this concept). We also though his drooping, hanging form would give him a unique silhouette and allow him to be expressive when landing and taking off.
Here's a shot showing the high-detail model before it's been textured:
As the primary ranged and support fighter on the alien team, he's able to shoot spikes or clouds of spores. He is the most nimble alien with the ability to fly, glide and roost.
The biggest change for the Lerk in NS2 is the switch back to spikes instead of bite (as in NS v1.0). We wanted to keep him as differentiated as possible and this seemed the easiest way to do it. It also doesn't seem very Lerk-like to have him fly up to a structure and then sit on the ground and bite it. He should be hiding in the rafters and in vents and attacking from range.
Spikes So his main attack is a rapid-fire spike attack. These don't have the super-long range as they did in NS v1.0 which means the Lerk must be in medium range to do damage to its target. The spikes fall with gravity and have some spread to them. They are good against marines and structures alike, although Skulks are more effective at bringing structures down quickly.
The alt-fire for spikes is new, although many community members will recognize it as an ongoing feature request. Alt-fire zooms his view and changes his spike attack into more of a sniper attack. This will let him hide in dark places and pick off marines. We also plan on adding a cool bit of flavor with this - if the sniper spike kills a marine standing near a wall, the spike will impale him up against it.
Spores The spore attack works like NS1 - it shoots a spore projectile that becomes a lingering spore cloud where it hits. Any marines in this spore cloud take damage over time. This is a great area control weapon and should allow Lerks to try to force marines out of an area, or prevent them from entering an area. We will probably still have heavy armor marines (info coming) be immune to this spore damage. We currently don't have an alt-fire attack for spores but are open to suggestions!
Roost We plan on allowing the Lerk to hold his crouch key when near a ceiling to flip upside down and roost there. When roosting, his view is upside-down and he's able to spike and spore from above. This is something I really wanted in NS1 and I can't wait to see it in NS2!
There are a couple upgrades planned for the Lerk as well, including Adrenaline, which increases his energy recuperation and Piercing which adds extra damage (and a satisfying "crack" sound) to the spike alt-fire.
Here's a video showing the completed Lerk in action: