Provided herein are methods and compositions for single cell characterization using affinity-oligonucleotide conjugates, including tetramer-oligonucleotide conjugates (e.g., pMHC-oligonucleotide). In some aspects, such methods may comprise the steps of: forming a vessel comprising an affinity-oligonucleotide conjugate and a T cell; attaching a vessel barcoded polynucleotide or complement thereof to: (a) an oligonucleotide portion of a pMHC-oligonucleotide conjugate, and (b) a T cell receptor (TCR) polynucleotide originating from the T cell; and sequencing the oligonucleotide portion or a complement thereof and the TCR polynucleotide or a complement thereof. Additional methods provided herein include determining the binding affinity of a T cell receptor (TCR) to a pMHC-oligonucleotide. Compositions of the present invention encompass a plurality of vessels, wherein a vessel of the plurality of vessels may comprise a single T cell; and a vessel barcoded polynucleotide, wherein the vessel may further comprise a pMHC-oligonucleotide conjugate.