Lynn Sr. is stern, and often calls a halt to his kids' fights, but he loves and cares about them. He also loves his wife, and often acts playfully romantic towards her. He has been shown to have a childlike side at times, even sometimes taking part in his kids' antics, when it's all in good fun. He's also the more sensitive of the two parents, often necessitating his wife, and stepping in whenever he needs to pull himself together.
On a side note, he seems to enjoy jokes and dancing. He is shown to dance on occasions in episodes such as "The Loudest Yard", "Ties That Bind", "Come Sale Away", "House Music", and "Lock 'n' Loud". It is mentioned in "A Tattler's Tale" that he won a dancing contest and received a disco ball that Lincoln broke. In addition, in "Sleuth or Consequences" he mentions enjoying karaoke. On occasion, he enjoys Luan's jokes, and tries making his own, which appeal to Luan as well, as shown in "Raw Deal".
He is also shown to be quite a coward; as he screams and faints at the sight, sound, and idea of spiders, as well as Lana's mud wrestling, horror movies, and Halloween.
Appearance
Lynn Sr. wears a sea green sweater over a light green checkered collar and cuffs, brown slacks and shoes. He has a long pointy nose, brown eyebrows, and curly brown hair that is thinning on the top.
In "House Music", when he is playing the cowbell, he wears a yellow-striped shirt, and green pants which his underwear was seen. In his youth, he sported a mustache, though he seems to have shaved it by the time he met Rita. His hair was also straighter and parted in the middle.
Trivia
Lynn Sr.'s entire face was never shown during the first season. His face was revealed along with Rita's face in the Season 2 premiere "11 Louds a Leapin'".
He is the first character in the series, apart from Lincoln, to speak to the audience. This instance occurred at the end of "It's a Loud, Loud, Loud, Loud, House".
It is revealed in "House Music" that he used to be in a band, but got kicked out due to playing his cowbell too much, even when they were not practicing.
Lynn Jr. - Love for sports ("Toads and Tiaras" and "Attention Deficit").
In "Fed Up", it is revealed that Lynn Sr.'s astrological sign is Libra, which means he was born on or somewhere between September 23 and October 22.
This episode also reveals that coconut milk and three-bean salad are bad for him.
The colors and styles of clothing that the Loud and McBride parents wear correspond with each other. Lynn Sr. and Harold both wear sweaters and brown loafer shoes. They also both have thinning hair.