I still have to stand behind the Kalani being the Rat and the Assasin. The thief, on the otherhand, was Bill.
Here is my interpretation of a timeline for Kalani:
Kalani flew into LAX from Hawaii . Coming in loud, they were swarmed by zombies and only 3 people made it off the tarmac including Kalani and Hannah.
Kalani and company saw a group of survivors from the window of a nearby hotel and ran to them.
These survivors were in fact the Mallers although he let Michael and company believe they went straight to the Other Tower.
The Mallers recognized Kalani's special relationship with Hannah and used that as leverage to get Kalani to work for them, specifically to infiltrate the Other Tower. I believe Scratch probably detailed to Kalani exactly what she would do to Hannah if she did not have his full cooperation.
When Kalani starts working for the Mallers he is given the nickname "Kalani". We know the Mallers all use nicknames and Datu mentioned that his name did not match his face when first meeting Kalani in the Arena.
While in place at the Other Tower, Kalani is found out. I suspect something he did might have lead to the security breach that let in the One With The Markings.
When the Other Tower fell, Kalani was taken to the Arena.
After being rescued by the "We're Alive" Tower, Kalani is put on guard duty.
He uses this opportunity to contact the Mallers to let them know he's still alive and ensure Hannah's continued safety.
The Mallers are happy to learn they now have a man inside the "We're Alive" Tower and also learn about the missing guns and the upcoming party.
The Mallers then mobilize for their seige on the "We're Alive" Tower.
In Season two, Kalani goes with Angel on a mission to collect the MREs.
Kalani gets very nervous that Angel is unexpectedly contacting the Mallers. Scratch would not have been happy that Kalani failed to forewarn her of such a meeting.
When Angel tells him the body they are carrying is Latch, Kalani quickly denounces any knowledge of who Latch is to conceal his ties to the Mallers.
When meeting up with Skittles, Skittles said he recognized Kalani. This was probably from his time at the Other Tower, since Skittles was reported to have been there when it was overrun.
Twice on the mission, Kalani tells Angel to leave him to die.
I think Kalani may have hoped his death would somehow keep Hannah safe, that Scratch would have no need to threaten/harm her with Kalani out of the picture.
After Angel refuses to let him give up, Kalani becomes loyal to Angel and the "We're Alive" Tower, and ends all contact with the Mallers, hoping they'll assume he died. Perhaps he hoped to be reunited with Hannah one day or was just consoled with the idea that she would still be alive somewhere.
When Pippin arrives there is now someone who could ID Kalani and either tell the Tower of his past connection with the Mallers or tell the Mallers he is in fact alive.
On the day Kalani and Datu head out to work with the Jolly Green Giant:
1. Datu is in the Parking Garage getting the car ready while Kalani goes to to tell Michael (on the 5th floor) that they are leaving.
2. Kalani then goes down to the 4th floor and cuts the wire in the hall before ducking into a neighboring apartment.
3. Angel leaves the Guard Room and heads up to the 5th floor Armory.
4. Kalani slips in, shoots Pippin and takes out the radio/communications.
5. Kalani heads down to the Parking Garage and leaves with Datu, who had the music turned way up.
6. Kalani checks in with Burt over the radio and "learns" that communication with the Tower is out, giving the impression that they were en route at the time of the shooting.
With Kalani no longer in contact with the Mallers, Hannah is now dispensable, to be used in the fake Lizzie hand-off.
Scratch is true to her word in how Hannah is killed. This is also a message she would want to send to Kalani in the event that he was still alive. Scratch would want Kalani to know it was Hannah, and that his actions lead to her death.
When Kalani hears about the fake Lizzie and how she was killed, he is convinced this red-head girl had to have been his Hannah.
In a heroic act of redemption, Kalani sacrifices himself for the Tower members he once betrayed. He tells Angel he hid his journals in Bill's desk which includes the story of all his dealings with the Mallers.
Kalani also tells Angel "That girl, that was my Hannah". This was the final peice of information Angel would need (after reading his journal) to piece together why he did what he did.
