Catherine had kept her promise, so far.

But something had changed tonight. For the first time since discovering her in that hospital ward, Catherine had been working with Sara tonight.

She knew the guys had started to get suspicious, and she wasn't surprised in the slightest. The first couple of hours had been fine, but gradually Sara had become quieter and paler, until eventually she had to take herself outside for some fresh air.

Back at the lab, she had claimed a stool at the layout room table and made every available effort not to leave it. When she had no choice but to stand up, it had been a visible struggle.

At lunchtime, Catherine had brought them both a sandwich. Sara had stared intently at hers, but every attempt to eat it resulted in a wave of nausea, until she had given up and resigned herself to a night of hunger – one of many, Cath suspected sadly.

Finally, at the end of her shift, she had left the lab, only to spend five minutes sat in her car in the parking lot trying to muster the energy to drive herself home.

It was now abundantly clear that Sara could not possibly continue like this for much longer. Even if she didn't tell the boys herself, they'd figure it out on their own. Doc had a head start due to his medical degree, but the rest of the team weren't exactly ignorant either.

Catherine had pulled out of the parking lot just a couple of minutes after Sara and initially headed to her own home, before making a sudden decision and turning around.

She needed to have this conversation with Sara now, while it was fresh in her mind. And this time, she wasn't going to back down. Puppy-dog eyes be damned, she was not backing down!

She spotted Sara's car easily, parked up in her usual spot, and pulled in beside her. She knew that her friend must have only just beaten her here and may not have even made it to her apartment yet.

However, it wasn't until she got out and set off walking across the parking lot towards the building that she actually saw Sara herself.

"Oh no." She breathed, taking off at a run. "Sara!"

She landed ungracefully beside her colleague, attempting to shake her awake.

The brunette had made it all of two steps up the stairs before collapsing.

x X x

The ambulance ride was largely a blur, at least until Sara started to come around as they pulled up outside the ER. Just as her dark eyes started to flutter open and Catherine's stomach finally unclenched, the ambulance ground to a halt and the doors were thrown open.

Suddenly, Sara was wheeled out and Catherine found herself scampering down the hall, barely able to keep up and follow the medical jargon at the same time.

Since it had already been established that she had no apparent injuries apart from the bump on her head, she was taken straight into a cubicle, allowing Catherine to remain close by throughout her examination and treatment.

And that was where she remained still, sitting quietly beside the bed while Sara slept off her headache, when a pair of hands appeared on her shoulders.

"I supposed I shouldn't be surprised that you beat me here." Nancy declared.

"What are you doing down here?" Cath asked hoarsely, straightening up in the hard plastic chair and allowing her back to click.

"The admitting nurse called up to our unit." She explained, leaning over the patient to give her a cursory check. "I wanted to see how she was doing?"

"Oh, she's great." Catherine sniffled, clawing a hand through her hair. "That's how she ended up at the bottom of a flight of stairs."

"I did warn you that this would happen." Nancy pointed out, taking a seat on the edge of the bed and resting a hand casually on Sara's leg, satisfied that she was not in any imminent danger. "She's going to get worse before she gets better."

"She hasn't been eating properly." Cath mused, propping her elbows on the mattress and staring intently at Sara's face. "Probably not sleeping either."

"And looking at her chart, I'd wager that she's missed a few of her tablets." Nancy hummed.

"You're right." Cath sighed sadly. "It's not working, me trying to take care of her like this. I need to find a better way, or she's just going to keep ending up in here."

"It's not your fault, Catherine." Nancy assured her. "People with Sara's kind of illness really need someone there all the time providing more consistent care. Unless she's willing to accept carers attending her home regularly, or move in with someone who can provide care to her, she's going to struggle to beat this thing."

Since Catherine didn't appear to have heard a word she said, her attention still completely focused on Sara, Nancy leant down and pressed a kiss to her hair, before leaving her sister to her contemplating in peace.

Except Catherine had heard her; and suddenly the answer seemed so damn obvious.

x X x

Sara hadn't stirred when Catherine had slipped out of her cubicle, which was just for the best really.

Since her car remained at Sara's apartment building, she had hailed a cab and in no time at all she was back where she had started the morning, with a new plan in her mind and Sara's door key in her pocket.

Maverick was pleased as always to see her, although probably wondering why his elusive owner hadn't arrived home.

Catherine scooped him up into her arms, ruffling the fur between his ears affectionately.

"Well little buddy," she exhaled, casting her gaze around the apartment. It was a good thing Sara didn't own that much – it would make packing so much easier. "I guess you're coming with me too. Lindsey will be thrilled..."