Since Ruto's return to the village and his assignment to work or die, Ruto had been drowning himself in his research. This wasn't something he minded doing, even if he'd prefer it under other circumstances. No matter what others in the village might say, Ruto was a Mikatakujira through-and-through, and was invested in scientific progress above most everything else.
And the time investment in his research had been going well. Ruto was able to produce decent results, and sending reports back to the village with the documents outlining his procedures, as well as the bacterial fruits of his labor, was at least demonstrating to his captors that he was taking this seriously and was not wasting his time. He was rewarded by the return of an old assistant.
Tokonatsu Yukari...
To say that Ruto had any particularly strong feelings about them would be a lie. They had always been a useful colleague, reliable and intelligent, and all too willing to cling to Ruto's coattails. They knew how to keep things quiet, and knew even better how to blind themself to what Ruto was obviously doing. They did a fantastic job of manipulating themself, so Ruto hardly even had to try.
Having them back in the lab had been very helpful in terms of efficiency, though perhaps Ruto found it the slightest bit stifling. The lab Ruto had been allowed was incredibly small and makeshift, which meant close work could at times be claustrophobic, and over the last several years Ruto had become accustomed to working alone. Despite their passingly friendly demeanor, they were a loner at heart and dreaded being near to others.
Maybe that was why the fact they were late didn't even cross their mind.
Ruto had gotten caught up with some little side project. Someone sleeping in an alley in false Takigakure had a miserable cough, rattling and loud enough to draw his attention when he'd walked by. Eternally compelled by curiosity and some strange kindness that had been struggling and half-failing to thrive inside him for decades, he dropped by to offer aid.
Squatting on the stone, Ruto was slowly preparing for an illness extraction technique right here in the alleyway, talking to the man all the while.
"-for months, you say? That must've been making it very hard to sleep. This should help repair your lungs quickly, though I'll leave you with some medicine as well to prevent any reinfection. Now, this technique can be quite painful, so I'll be providing you a pain reliever first..."