Who Would Admit Their Love Rival Is Their Grandpa?

A multiple time-travel premise. Readers interested in time-travel stories, jump right in! 1. Xu Ying, a 22-year-old agent, is ordered to get close to an old man and extract information from him. Xu Ying takes a look at the target's photo and is so shocked his pupils tremble. "He's 83?" "Eighty-three." His superior nods slowly. How can an 83-year-old man look like that? That's just unfair. His superior says, "We suspect he's infected with an extremely dangerous brain-eating bacterium. Because he's been taking suppressants for a long time, he still looks the way he did when he was young." Xu Ying glances at the photo again. This man is... far too handsome. "Then why are you sending me to get close to him?" "Well, there's a rumor that he once... had a relationship with your grandfather." ...What? "And you look almost exactly like your grandfather." ...What??? "So even after all these years, you're probably still his type." ...What???? Cursing under his breath, Agent Xu Ying sets off on his undercover mission in a foreign land. 2. Zhen Ze, a 27-year-old veterinarian, runs a pet hospital. Aside from being ridiculously good-looking, there's nothing particularly suspicious about him. Zhen Ze's daily life mainly consists of caring for all the fluffy little darlings at the hospital and fending off the countless admirers who are desperate to get their hands on him. "Zeze, I had a fortune-teller check our compatibility. We're made for each other, destined to love one another for all eternity~~" "Zeze, pick me! I'm strong and virile, and I'm amazing in bed!" "Little Zeze, be mine, and I'll give you a life of luxury and riches!" The beauty sighs: Thanks, but all I want is to spend every day taking care of the fluffy ones at the hospital. "Damn it, why am I not fluffy? I'd give you my life just to have your lovely hands touch me once!!!" In short, veterinarian Zhen Ze's everyday life is perfectly, utterly ordinary. Until one day, a man named Xu Ying forcibly moves into his pet hospital to stay. The man is fierce-looking, tall and strong, and powerful enough to take on a hundred people at once. Ordinary people wouldn't dare mess with him. Yet despite going to great lengths to move into the pet hospital, the man is inexplicably wary of Zhen Ze at every turn, watching him with suspicion. Huh? This guy's different from the men who usually approach me, Zhen Ze thinks. But he's so good at fighting, surely nobody else would dare come near me? Great, you're going to be my human shield against all my admirers. Zhen Ze happily accepts the fact that he'll be living under the same roof as Xu Ying. But why does this human shield of a man seem to suspect that I'm 83 years old? Zhen Ze can't figure it out. Then one day, a huge time-space wormhole appears before veterinarian Zhen Ze. Suddenly, Zhen Ze transmigrates to several decades in the past. Blurb written July 21, 2023 (The blurb may be tweaked a little once the story officially begins, but the main points will stay the same.) Note: The love interest will not change! The love interest will not change! The love interest will not change! Theme: Make the most of a limited life and shine with boundless warmth