Sometime prior to The Lost Lapras, the herd came past Tangelo Island where a young Lapras became separated from the herd and ended up washing ashore. Ash caught the Lapras, promising to return it to its family.
In Viva Las Lapras, the Lapras herd were travelling past Tarroco Island when they were spotted by Ash's Lapras who was excited to see his family again. One of the Lapras was happy to see it again but the others weren't as it was with humans so the Lapras attacked it before escaping. They reappeared later on having come under attack by a group of pirates led by Captain Crook. Ash and his friends were able to save the Lapras herd allowing Ash's Lapras to rejoin the herd before they swam off.
Johto
In Lapras of Luxury, the Lapras herd reappeared where Ash was reunited with his Lapras. Their reunion was cut short when Team Rocket attempted to catch the Lapras herd. With help from Ash, his Lapras, Brock, and Misty the herd were freed and helped send Team Rocket blasting off. As the herd were about to leave, the leader decided to make Ash's Lapras the new leader which it accepted.
In Ride, Lapras, Ride!, the Lapras herd briefly appeared when Ash's Lapras returned to them after reuniting with Ash.
Personality and characteristics
When they first appeared, the Lapras herd showed a scared of humans. This was because they had previously been attacked by a group of pirates whilst in a no-capture zone. On seeing one of their young with Ash and his friends, they initially rebuked the Lapras, refusing it to rejoin the herd though it mother showed reluctance, wanting it to rejoin the group. This changed later on when Ash and his friends saved them when they were attacked by Captain Crook and his pirates. Once they were saved, they allowed Ash's Lapras to rejoin the herd.
