Peptides have been identified that bind with high affinity to dyed hair. Peptide-based hair reagents formed by coupling a dyed-hair-binding peptide to a benefit agent are described. The peptide-based hair reagents include peptide-based hair conditioners and hair colorants. The peptide-based hair conditioners and hair colorants are comprised of a dyed-hair-binding peptide coupled to a hair conditioning agent or a coloring agent, respectively. The peptide-based hair reagents or the dyed-hair-binding peptides may also be used as a protective sealant to improve color retention of dyed hair.