While Little Sisters aren't exactly enemies, strictly speaking, they're the most powerful (and valuable) creatures in BioShock. In the first game, you could also research them (not in the second, though. Grr). Little Sisters have been pretty much perfect since design, so there's no need to change much, except for one thing...
- Level 1: EVE Expert Gene Tonic
- Level 2: Max Health and EVE increased
- Level 3: Demanding Father Gene Tonic
- Level 4: Max Health and EVE increased
- Level 5: Little Sister will refill the player's Health and EVE to full after gathering ADAM
Nothing much. 2K said that the Little Sisters would be able to heal their Big Daddy if they killed you, but I haven't seen that happen. That could be the only change at the beginning.
Now this is where it gets more interesting. After the midpoint, the Little Sisters you'll encounter will have offensive abilities of their own: under certain circumstances, they'll release a random Plasmid attack at their enemy. The plasmid can be Electro Bolt, Incinerate!, Winter Blast, Insect Swarm, Telekinesis, Chrono Warp or Gravity Well. The Little Sister will fire a random Plasmid under the following circumstances:
- If she gets hit by any form of attack. Child cruelty has never been punished so painfully.
- If her Big Daddy is on the verge of dying (about 25% health or less).
- If attacked while gathering ADAM. This may work for you, as the Little Sister would be able to kill a few Splicers on her own if you've let your guard down.
And that does it for the Little Ones. Next up: Big Daddies!