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We present a noteworthy transient AT 2021aeuk exhibiting three distinctoptical flares between 2018 and 2023. It is hosted in a radio-loud narrow-lineSeyfert 1 (NLSy1) galaxy, with an optical image showing a minor tidalmorphology and a red mid-infrared color W1-W2=1.1. Flares II and III exhibitrapid rises, and long-term decays (around 1000 days) with recurring after-peakbumps. The g-r color after subtracting the reference magnitude exhibited arapid drop and recovery during Flare II, followed by the minor after-peakevolution in blue colors. We applied a canonical tidal disruption event (TDE)fitting on the light curves which gives a decay index p of$-2.99_{-0.14}^{+0.13}$ for Flare II and $-1.61_{-0.65}^{+0.34}$ for Flare III.The blackbody fitting shows lower temperatures ($\sim 10^{3.8}$K) with minorafter-peak evolution. The blackbody radius ($\gtrsim 10^{16}\ \rm cm$) andluminosity ($\sim 10^{45}\rm erg\ s^{-1}$) are larger than the typical TDEsample's. The time lag (in rest frame) between ZTF g- and r-band ($\rm\tau_{g,r}=3.4^{+1.0}_{-0.9}$ days) significantly exceeds the prediction fromthe standard accretion disk. Pre-burst spectra reveal prominent Bowenfluorescence lines, indicating a vigorous or potentially long-lasting processthat enriches the local metallicity. Additionally, we derived black hole massesof $\log\it{M}_{\bullet}\rm=7.09^{+0.18}_{-0.31}\ \it{M}_{\odot}$ and$\log\it{M}_{\bullet}\rm=7.52^{+0.08}_{-0.10}\ \it{M}_{\odot}$ using $\rmH\beta$ and $\rm H\alpha$ emission lines. The variation and recurring featuresof AT 2021aeuk are not likely induced by the radio-beaming effect or Type-IIsuperluminous supernova (SLSN-II), however, we cannot rule out the possibilityof TDE or enhanced active galactic nuclei (AGN) accretion process. Theunusually high occurrence of three flares within five years may also induced bythe complex local environment.

Gleeok's Fire-breathing: Triple Flares of AT 2021aeuk within Five Years from the Active Galaxy SDSS J161259.83+421940.3