Ghaile was a historian for the skrall before the split, and was responsible for remembering not only their history but also ancient battle tactics that had led their ancestors to victory. When the male and female skrall divided themselves, she was one, along with Ronin, of those who resisted the movement.
When the Core War started and the Great Beings started to finish the Mata Nui project, she saw it was her only reliable shot at survival. Her and a few others managed to board the robot via one of the bonecavern entrances in it's feet – maintenance tunnels that ran through the robot like their namesake implied..
Skrall have amazingly long lifespans, and in the environment of the Matoran Universe, they were practically immortal. They kept themselves to themselves, secluded in one of the southern islands they named Baaeran, the skrall word for “silent life”.
Eventually, disaster struck. The matoran civil war breaks out, and matoran start to die. The kestora, unable to teleport any dead material to the Red Star for reanimation, are forced to choose someone to to the job for them, as they cannot leave the red star. They chose the skrall Gwillanna, Ghaile's unfortunate mentor.
The loss of her mentor had a bad affect on Ghaile, and he began to recant from her violent lifestyle. Eventually the Brotherhood of Makuta began to investigate the southern isles, and so found the skrall.
Being natural fighters and dedicated psionists, the skrall repelled them easily. However, they suceeded in capturing Ghaile – the only live skrall they had seen before. She was relocated to Destral where they performed a number of non-invasive tissue tests on her before sending her to makuta Enias's guild in the southern continent mining town of Neyinith.
Enias's guild had the sinister aim of finding new ways of creating – and controlling – toa. A series of experiments showed that toa and this new race – the skrall – shared over fifty percent of their genetic material. It was this finding that allowed Enias to see – to some limited degree – what allowed toa control of the elements.
He used this knowledge to try and force some matoran into toa-hood without the use of e-protodermis. The experiment went horribly wrong. The seventh subject ended up in an unnatural kaita with one of Enias's collegues and a skakdi guard. It was utterly unstable, and used a combination of water and gravity powers to flood the area. The six other subjects survived (as toa) including Ghaile, but Enias did not.
Ghaile spent five hundred years thereafter trying to find the rest of her race. She had limited success. Eventually she had a run-in with a member of Enias's toa subjects, who was after the kaita Enias had created. After the kaita killed the toa, Ghaile stole the mask from the dead body and proceeded to use it in mutilating the kaita.
It was at that point Ghaile met the skrall who had once been Gwillanna, now the Bonesnatcher and with none of her original memories, and had a chance to say goodbye to her.