When we investigate our system (Figure ), not surprisingly, we observed two major non-radiative states under the emissive π-π* state in MBTPA-Tz molecular state: 1) the dark n-π* state caused by the tetrazine unit and 2) the TICT state caused by the AIEgen. Those states were confirmed as dark states by their negligible oscillator strength values (f < 0.01). For MBTPA-Tz, tetrazine is conjugated with AIEgen; therefore, the access to the dark n-π* state is from internal conversion. We determined that emission quenching is due to both ICDS and TICT processes. Once MBTPA-Tz is aggregated, the dark state characteristics change. Restricted molecular configuration prohibits access to the TICT quenching state. Instead, we found a newly formed dark ET state whose hole and electron are separated in two molecules, accompanied by low-lying dark n-π* states induced by the tetrazine moieties. This result matches the intermolecular quenching effect observed in AIE-Tz molecules: close interaction between tetrazine and AIEgen induces PeT quenching and provides intermolecular access to the n-π* dark state through energy transfer as well as maintaining internal conversion pathways. In summary, MBTPA-Tz aggregate quenches emission based on ICDS, ETDS, and PeT processes. These multiple quenching pathways amplify the quenching effect of tetrazine and explain the experimental result of the aggregation-enhanced quenching effect of MBTPA-Tz (Figure ). Upon iEDDA reaction, the tetrazine moiety is damaged, and the tetrazine-triggered quenching states are henceforward eliminated. As a result, the pyridazine molecule exhibits different behavior. In the single-molecule state of MBTPA-Pz, the n-π* dark state is no longer observed, but the twisted-intramolecular charge transfer (TICT) state persists, resulting in weak fluorescence in dilute solution. However, when aggregation occurs, the TICT formation is restricted due to the limited free volume and hydrophobic environment in the solid state. Consequently, no quenching state exists beneath the emissive π-π* state, allowing for strong emission in the MBTPA-Pz aggregate. As a result, the emission of MBTPA-Pz is switched on as access to the TICT dark state is inhibited in the aggregate state.