For a star, its initial mass is everything. It determines how quickly it burns through its hydrogen and how it will evolve once it starts fusing heavier elements. It's so well understood that scientists have devised a "main sequence" that acts a bit like a periodic table for stars, correlating their mass and age with their properties.
The main sequence, however, is based on an assumption that's almost always true: All of the energy involved comes from the gravity-driven fusion of lighter elements into heavier ones. However, three astrophysicists consider an alternative source of energy that may apply at the very center of our galaxy— energy released when dark matter particles and antiparticles collide and annihilate. While we don't even know that dark matter can do that, it's a hypothetical with some interesting consequences, like seemingly immortal stars, and others that move backward along the main sequence path.
Dark annihilations
We haven't figured out what dark matter is, but there are lots of reasons to think that it is comprised of elementary particles. And, if those behave like all of the particles we understand well, then there will be both regular and antimatter versions. Should those collide, they should annihilate each other, releasing energy in the process. Given dark matter's general propensity not to interact with anything, these collisions will be extremely rare except in locations with very high dark matter concentrations.
