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Tear Jerker: Garfield
The 1984 Story Arc in which Garfield wanders away from home while Jon's at a convention and ends up stumbling upon the abandoned Italian restaurant where he was born. The strip has several tear-jerking moments, such as Odie trying to console Jon by abusing him like Garfield did; Garfield discovering that the restaurant is now abandoned; and finally coming home just in time for Christmas. It also subverts this trope on the December 23 strip, with Garfield collapsing dramatically in the front door; Jon asks if Garfield's okay and he replies, "Actually, yes, I just thought it would be more dramatic this way."
After Lorenzo Music (Garfield's voice actor) died, Davis made a drawing of Garfield, and his thought bubble read, "I'm speechless."
When Charles M. Schulz, creator of Peanuts, passed away, there was a strip with Garfield standing next to Snoopy's iconic red doghouse looking up at it, and then lying on top of it like Snoopy does and sighing sadly.
The 1989 Halloween arc where Garfield wakes up to find his home abandoned for years, and Odie and Jon are long gone. In one strip, when Garfield hears Jon saying, "Hello, Garfield. Have some food" and Garfield rushes in to find Jon and Odie in the kitchen, but they disappear in the next panel. It redeems itself by having a Heartwarming Moment where Garfield hugs Jon, saying, "Who needs [food]? I need you!"
Garfield's Christmas Special, as Jon's Grandma reminisces about her late husband, and how on Christmas Eve she misses him the most.
In one Sunday strip, Garfield muses about what his life would be like if he married Arlene, and envisioning that after their huge wedding, they'd have three kids together. The strip ends with him angrily declaring "Forget it! I'd make a lousy father," and walking out on his hypothetical family, who tearfully watch him leave.
In a series of strips where an chick thinks Garfield is his father, Garfield at the end of the storyline, tells him for the last time that he's not his father and tells him to leave him be and orders him to find his mother, once the chick leaves Garfield. Garfield sheds a single tear.
In Garfield Gets Real Garfield stares forlornly into a newspaper, which functions like a camera, after a long day of trying and failing to return home. He wonders if anyone is still even watching, before turning away. Arlene is, and what happens next turns this into a Heartwarming Moment.
Quite a bit of Garfield's Fun Fest, but especially near the end when Garfield almost gives up the competition after seeing Arlene and Ramone during their act.