Tholins are pretty interesting stuff, because there's some theorizing that they may have been the precursor to amino acids on Earth. They don't exist on Earth naturally anymore, because they oxidize very readily in the presence of free oxygen, but on a frozen methane iceball, they hang around quite a while as aerosol before eventually condensing into a red sludge.
Back in 1986, Carl Sagan was part of scientific team that synthesized Titan tholins in the laboratory and played around with subjecting it to different planetary chemistry effects, such as introducing water. What they found was that the tholins would break down into a host of compounds, including amino acids. The thought then follows that early Earth would have had a nitrogen-methane atmosphere suitable for producing tholins from solar radiation. Those tholins then reacted with a sufficient quantity of water (a comet perhaps) to produce a large amount of various amino acids, which (and here's the handwavium, at least from my limited understanding) eventually self-organized into the earliest cellular life.
There's an alternate explanation as well -- many common soil bacteria can subsist purely on tholins, deriving both carbon and energy. There may have already been bacteria on the primordial Earth, happily munching tholins when suddenly (in geologic time) those tholins start disappearing and they're awash in amino acids. This could have produced evolutionary pressure to start incorporating those amino acids into their own increasingly complex structures and allowing them alternative metabolisms that weren't dependent on tholins.
The upshot is that although unlikely, it's entirely possible that bacterial life could be living under that blanket of red sludge on Pluto. Not sure what that would look like, given the temperature extreme, but it's theoretically possible.