This image from Red Dwarfs and the End of the Main Sequence shows the evolution of a $0.1\,M_\odot$ star:
The x-axis is the effective temperature of the star (cooler on the right as usual), and the y-axis is its brightness.
Trappist-1 is a $0.09\,M_\odot$ star and this graph is applicable to its evolution.
The star begins life near the top right, following the Hayashi track (fairly constant temperature, but becoming less bright as the ball of gas (that isn't yet fusing Hydrogen) shrinks. This track is brought to an abrupt halt when hydrogen fusion starts in the core. This is the Zero Age Main Sequence "ZAMS"
Then follows a very very slow climb, the star slowly becomes hotter and brighter over a period of 5 trillion 742 billion years (I assume that the four figure accuracy here is overstated!) Trappist-1 would be somewhere near that ZAMS point, slowly slowly getting brighter, but it will live for so long that it is still very close to that corner, it's still really just a baby!
At this point an inert radiative core forms, and the star does a little turn on its track. It develops into a "blue dwarf", as it more rapidly burns out its remaining hydrogen, before cooling as a Helium white dwarf. They never enter a giant star phase, as the sun will.
It is not that young red dwarfs are brighter that imperils planets, it is the flares that they can produce:
Young red dwarfs are active stars, producing ultraviolet flares that blast out so much energy that they could influence atmospheric chemistry and possibly strip off the atmospheres of these fledgling planets. -Source