So ever since Shiro got Keith into the garrison and caused him to move back to the town he was born.
Meaning the desert and the blue lion.
Keith begins to hear the blue lion the moment he enters town, and in the garrison it is much closer to the desert making the blue lion's voice that much harder to ignore.
Taking Keith on as his protege, Shiro practically adopts him and in extension so does Adam.
The two become his gaurdians and take care of him and support him while he is at the garrison.
The blue lion isn't an obvious problem at first, just a small nudge or whisper in the back of Keith's mind.
Every once and a while blue nudges too hard and Keith checks out of reality, zones out to the point he is unreachable.
No one thinks much of it until it becomes a regular thing.
Disrupting his classes, his simulation runs and his daily life.
Shiro and Adam grow concerned.
Medication isn't considered at first, Shiro hoping some therapy will help Keith develop his focus along with reminders.
Patience yields focus after all.
But when Keith loses focus while out on a hoverbike run with Shiro leading to a trip to the garrison med bay.
Shiro begins to consider medication as an option.
Keith is against it at first, but the hoverbike incident keeps him from out right lashing out at the idea.
They start a trial of meds for focus.
At first Keith can't tell much has changed, there is still a nudge in the back of his mind, but it hasn't been long so he disregards it.
It's two weeks in Keith has a lapse of focus, it's in a simulation run, Keith isn't able to snap out of it quick enough to save his score.
That is the first sign.
They try many different medications and many different doses and the problem doesn't go away.
In his frustrations at another failed medication that only left him to deal with side effects that didn't even effect his episodes in any way.
He lets it slip after that, tired of the meds, that he'd be able to focus if his mind would just shut up for once.
Shiro and Adam don't immediately come to the assumption, but after a few sleepless nights of worrying while Keith sleeps restlessly, they wonder if Keith is hearing voices.
They confront him after classes on day.
And ask him directly, if he is hearing voices that aren't there.
Keith isn't stupid and knows the stigma of what hearing voices could mean.
But he is tired and frustrated with the episodes where he seems to lose touch with the world around him when the nudging and whispering get to loud.
So Keith tells them about blue.
He doesn't know blue is a giant sentient alien warship buried in the desert calling out to Keith because he is the only one sensitive enough to quintessence to hear them.
He assumes like any logical person who is hearing a voice in their mind that isn't attached to something in their immediate surroundings, that he is hallucinating.
This in turn instead of helping find effective treatments, just finds different types of the same treatments.
To pile on more worry, Shiro is assigned to the Kerberos mission around this time.
Adam is against this because he is not only leaving Adam, he is leaving Keith, with no guarantee he will return alive.
An arguement ensues which Keith witness the tail end of.
He watches Adam storm out and Shiro tiredly sigh and collapse onto the sofa.
Adam takes time to reflect on the news Shiro plans on going regardless and decides he can't let the fight disrupt Keith's only support system.
Adam goes to the launch for Keith alone, still feeling bitter and betrayed by Shiro.
Keith has an episode as the ship leaves the atmosphere, Adam takes Keith home after.
Keith while coping with the strain of over medication, decides to hold out until Shiro returns.
Adam on the other hand is struggling to cope, taking care of Keith was a partnership him and Shiro took on together.
Without Shiro, Adam has taken the full weight of that responsibility.
From coaching Keith out of fights, keeping him on his work load for classes, making sure he stays on his meds, keeps his appointments and eats his meals.
Adam fully realizes the gap in which Shiro once filled.
The new meds Keith starts after the launch have the lovely effect of making him move sensitive to quintessence, like a coffee shot to the brain in the morning, they turn the quintessence sensitive network in his brain on max.
Keith is completely unresponsive for several days.
Taking him off the meds doesn't immediately turn the sensitivity back down, it is a slow gradual decline back to manageable.
Meanwhile Keith is hospitalized due to not being fully awake and aware enough to feed himself.
Multiple times he attempts to sleep walk while entirely unresponsive to where ever blue is calling from.
After that episode Keith wakes in a psychiatric ward with no clue how he got there.
Adam had put a stop to the drug treatments after Keith's extended episode, and Keith is to stay in the ward for long enough to ensure a lengthy episode like that won't become a regular thing.
It's in this ward Keith learns Kerberos was lost.
Keith lashes out, at Adam, at the doctors and nurses.
He refuses to accept it.
And this is where Blue steps in to poor gasoline on the inferno.
After Keith calms down and secludes himself to try and accept the news, blue nudges him again.
Telling him to go-to the desert, wait for an arrival, that he must go.
Keith latches onto this, needing a distraction from the news Shiro is never coming home.
After several escape attempts Keith becomes a flight risk and is kept in more secure accommodations.
The episodes gets worse as Keith begins to listen to blue more instead of ignoring her as he did before.
When in a trance he somehow slips past his watchers easier then when not in a trance.
But he still gets caught in the act trying to leave every time.
The increased episodes is what makes his stay at the ward longer.
He originally was only meant to stay temporarily to monitor his episodes to make sure they aren't getting worse after the extended med induced episode.
So him listening to blue and having more episodes more often, sleep walking episodes at that, means he has extended his stay in the ward for his own safety.
Adam can't watch Keith twenty four seven.
Keith is still in the ward the night Shiro falls back to earth.
Keith has been in a month long trance building up to the arrival, not entirely aware of the time passing around him, only knowing blue is urgently nudging him and he has to go.
The garrison trio rescue Shiro from quarantine without Keith, and they find the blue lion.
Keith hears blue wake up, suddenly she is clearer then she has ever been before, just as suddenly their connection is gone and his mind is quiet.
Keith is left dazed and lost, with no idea what is going on.
Blue in the meantime has switched to harrassing Lance who now sits in the pilot seat.
Blue wants Lance to go pick up Keith before they leave.
So a giant blue lion crashes into the courtyard of the garrisons psych ward and Keith is just like staring out the window wondering if he has finally lost his mind.
Keith feels the familiar nudge and realizes this, this lion in front of him, is what has been calling to him all along.
So Keith books it out of the ward, dodging the doctors and nurses attempting to get a hold on the situation and hops into the lion.
The rest is basicly canon, except Keith is recovering from unneeded drug treatments and the atrophy of being a literal vegetable for weeks at a time.