  The strong coupling phase diagram of magic angle twisted bilayer graphene
(TBG) predicts a series of exact one particle charge $\pm 1$ gapped excitations
on top of the integer-filled ferromagnetic ground-states. Finite-size exact
diagonalization studies showed that these are the lowest charge $\pm 1$
excitations in the system (for $10$nm screening length), with the exception of
charge $+1$ at filling $-1$ in the chiral limit. In the current paper we show
that this "trion bound state", a $3$-particle, charge $1$ excitation of the
insulating ferromagnetic ground-state of the projected Hamiltonian of TBG is
the lowest charge $+1$ overall excitation at $\nu=-1$, and also for some large
($\approx 20$nm) screening lengths at $\nu=-2$ in the chiral limit and with
very small binding energy. At other fillings, we show that trion bound states
do exist, but only for momentum ranges that do not cover the entire moir\'e
Brillouin zone. The trion bound states (at different momenta) exist for finite
parameter range $w_0/w_1$ but they all disappear in the continuum far below the
realistic values of $w_0/w_1= 0.8$. We find the conditions for the existence of
the trion bound state, a good variational wavefunction for it, and investigate
its behavior for different screening lengths, at all integer fillings, on both
the electron and hole sides.
