Recurring characters

Other major characters include Megan, Marvin's cousin; Janet, who is Megan's mother and Jenny's sister; Ming Ming, Janet's adopted daughter from China; Bea and Roy, Marvin's maternal grandparents; and Doris, Marvin's paternal grandmother.^[3] Megan's father has not been seen (the strip indicates Megan's parents are divorced). Minor characters have included Bea and Roy's toy schnauzer named Junior;^[4][5] Roy's friend Bernie; and Marvin's friends Jordan, Warren (who is a genius,^[6][7] with a 174 IQ^[8]), Kyle,^[9] Gerald^[10] and Will, a child prodigy who spelled "prodigy" at five months.^[11][12] Jeff has a macho friend, Ted.^[13] Jordan has a girlfriend Shillina.^[14] Marvin's goldfish are Finn and Gill.^[15] As of 2022 Jordan has a baby sister Lici.^[16] Marvin's paternal grandfather has a cat named Clawfull.^[17] As of 2024 Marvin has a classmate named Wayne Johnson who can lift heavy things.^[18]

Prior to 2013 the strip's name was simply Marvin.

Continuity

Continuity is similar to that of Garfield in that milestone events affect future storylines but dramatic events occurring in one day's strip may be ignored in the next: in the strip that ran on October 4, 1982, Marvin shaves his head with his father's electric razor, but the next day his hair is back to normal. The strip's characters age irregularly, as is common in comics and other media (see soap opera rapid aging syndrome). Marvin is identified as less than 1 year old in the December 16, 1999 strip, where he states it is his first Christmas, but in later strips he states he is two years old. He learned to walk all at once on July 16, 2003.

In earlier strips, the baby characters did not speak, save for occasional crying, but were capable of understanding each other telepathically, an ability seemingly lost by adulthood. Animals shared this power to communicate without spoken words, communicating both with each other and with the babies.

Early strips often featured puns; in later strips, much of the humor comes from the babies' limited understanding of the world around them. For example, Marvin wonders about an approaching winter by thinking to himself "Why is now the time when people put their clothes on..." then looking out the window at a tree with shedding leaves "...And trees take theirs off".

Suspension of disbelief

Events in Marvin are portrayed as real, no matter how fantastic; there is never a story in which a baby's dramatic experiences are shown in the end to be ordinary happenings when seen by an adult's wiser eyes. These storyline elements include the frequent appearance of Santa Claus around Christmastime along with in-universe parallels of contemporary happenings; for example, one baby made hundreds of millions of dollars operating a website called cryspace around the time that MySpace was most popular among readers of the strip, and his fortune generates plot elements in later strips.

Milestone events

Some events in the history of the strip are reflected permanently in the future strips.

Bea and Roy Arnold^[19][20] lost their retirement savings in the 2008 recession and had to move in with Jeff and Jenny; Janet did not have enough room.^[19][21] As of 2021 the grandparents are no longer living with the family.^[22]

In 2010, the Millers got new neighbors, the Purfects, who are so perfect they make the Millers feel inadequate. Rodney Purfect has a PhD and is a company president, has won the Heisman Trophy and climbed Mount Kilimanjaro. He is six feet five inches tall and very manly. Barbie Purfect is a blonde housewife who attended cooking school in Paris, was a cheerleader, class president and sorority president. Rodney Purfect II is two and a half years old but reads at a third grade level, performed his piano composition for Queen Elizabeth II and was potty trained at 6 months.^[23] He also has blond hair.

In 2005, Marvin guest starred in the comic strip Blondie for its 75th anniversary.

In 2019, Jeff's mother was kicked out of her retirement home and moved in with the family.^[24]