Lance and Lotor began as enemies. Throughout Season 3, Lance along with the paladins always fought against Lotor. Eventually when they captured him, Lotor ended up getting locked in the Castle of Lions. Eventually the paladins were able to trust Lotor, and ended up witnessing him defeat Emperor Zarkon. Lance began to trust him and eventually the two began working together as allies.
During Lotor's alliance with Voltron and the paladins, he began to develop romantic feelings for Allura. This caused Lance to grow jealous and believe he could never compare to the prince, after Lance's many obvious attempts to impress Allura in the past. Lance was seen to make snarky remarks about Lotor during the time he was jealous.
When Lotor was revealed to be evil courtesy of Keith, Krolia and Romelle. Lance had completely lost his trust in Lotor and they became enemies once again. This is further highlighted when Lance shows little to no mercy once Lotor is defeated by Voltron. Just as Lotor shown no mercy towards Lance after Honerva freed him and his ship from the vail. During Lance and the Paladins' "trip" through Honerva's mind, they learn that Lotor is dead and how his mother plans to seek out a perfect reality where she can be with him and Zarkon again. Even though Lance and his allies had failed to stop Honerva merging her ship with Lotor before she goes through the portal, they were able to repair the damage she caused. Lance sees Lotor's spirit reuniting with his mother before he and the other human paladins were sent back home to their reality.
Lance listening to Allura talk about Lotor having good intentions despite being misguided, he realises that there was good within Lotor and his family. The former paladin teaches this lesson to others while spending time with his own family.
Before Lotor was officially introduced on the show, fans would theorize as to how he would interact with the Paladins. Some fans thought that Lance would be in some way jealous of Lotor's hair, and his flirting with Allura. There were also a lot of fan art of evil Lance alongside Lotor. Royalty AU's are also popular in the pairing.
Some will depict Lotor flirting with Lance and ignoring Allura, in both fan art and fan fiction. Snarky back and forth are also popular as well. Typically when Lotor flirts with Lance, he will snarkly reject him. Normally Lance is being shown to be put off by Lotor's advances. The darker side of these portrayals, show Lotor pursuing Lance past the point of comfort and hurting the other paladins in the process.
On AO3, Lancelot is the 14th most written ship within the fandom; Lotor's most written and Lance's fifth.
|SHIPS||het||Allurance • Allurivan • Hallura • Hidge • Hunay • Hunelle • Jamonica • Kacxa • Kallura • Kidge • Komelle • Krolidad • Krolivan • Leiffin • Lotacxa • Lotura • Mallura • Nymatt • Plance • Romatt • Romance • Shallura • Shidge • Zaggar|
|slash||Adashi • Corance • Hance • Heith • Jaith • Katt • Keitor • Klance • Koliveith • Lancelot • Latte • Shance • Sharkon • Shatt • Sheith • Shendak • Shlav • Shotor • |
Shunk • Svance • Svav • Sveith • Uliro
|femslash||Acxlura • Kromelle • Pallura • Romura • Shayllura • Veracxa • Zezor|
|poly||Jeiro • Pallurance • Sheitor • Shklance|
|CHARACTERS||m/f||Allura • Hunk • Keith • Lance • Lotor • Matt • Pidge • Shiro|