Leon's story was different in Resident Evil 1.5, the prototype version of Resident Evil 2. Still the unlucky rookie cop, instead of coming into town upon Raccoon City's destruction as he did in the final version, in the original draft, Leon and a small group of cops are holed up in the Police Station, having battled fiercely since the beginning of the incident. Leon had entered service a few days prior. The Precinct would be compromised shortly before the start of the game, and Leon would declare to the surviving morale-drained cops that they have to brave the gauntlet of horrors outside and escape or be doomed to wait for their death as the game starts. Leon's scenario originally had two supporting characters: Marvin Branagh and Ada Wong (who instead wore a researcher's outfit, and was known as "Linda").
Leon had two different character designs, but Capcom eventually settled for the way he looked in the final version of Resident Evil 2. When Ayumi Saito interviewed producer Shinji Mikami, he claimed that Leon's original design looked too much like Chris Redfield. In the conceptual designs for Leon, there are numerous illustrations of him and Elza Walker (the early version of Claire) wearing an armored vest with Umbrella's logo and the acronym U.S.S. (suggesting that it belonged to the Umbrella Security Service, HUNK's unit). This was part of a proposed armor system for Resident Evil 1.5. A casual portrait of Leon with a bloodhound was featured in Resident Evil 1.5's promotional artwork, and one piece of Leon's armored artwork was re-purposed for the box art of Resident Evil Gaiden.
Leon also went several iterations in Biohazard 3.5 (Resident Evil 4 development). Leon, in one of the earlier version, was to infiltrate the mansion belonged to Oswell E. Spencer. The location was later used in Resident Evil 5 DLC Lost In Nightmares. Instead of injected with the Las Plagas, Leon was originally infected with the Progenitor Virus, causing him to hallucinate supernatural enemies. Another of Leon's earlier iterations in Biohazard 3.5 was scrapped and reused in a new series called Devil May Cry, with the early Leon being recycled into the Dante character.