| Episode cast overview, first billed only: | |||
| Tom Welling | ... | Clark Kent | |
| Kristin Kreuk | ... | Lana Lang | |
| Michael Rosenbaum | ... | Lex Luthor | |
| Eric Johnson | ... | Whitney Fordman | |
| Sam Jones III | ... | Pete Ross | |
| Allison Mack | ... | Chloe Sullivan | |
| Annette O'Toole | ... | Martha Kent | |
| John Schneider | ... | Jonathan Kent | |
| Kelly Brook | ... | Victoria Hardwick | |
| Kevin McNulty | ... | Mr. Summers | |
| Sarah-Jane Redmond | ... | Nell Potter | |
| P. Lynn Johnson | ... | Mrs. Summers | |
| William Samples | ... | Sir Harry Hardwick | |
| Tom O'Brien | ... | Roger Nixon | |
| Shawn Ashmore | ... | Eric Summers | |
Clark and a classmate, named Eric Summer, are both struck by lightning when Eric is holding a piece of meteor rock. The electrical surge takes Clark's powers away and transfers them to Eric. As Eric gets used to his new powers, Clark has to deal with being a normal person for the first time, with all the advantages and disadvantages. But Eric's abusive and domineering father wants to have him examined in Metropolis for his strange powers and in response, the mentally unbalanced Eric goes on a rampage. Meanwhile, Sir Harry Hardwick, Victoria's father, and rival of Lionel Luthor, try to recruit Lex for their business in Metropolis and almost succeed in buying out Luthor Corp. But Lex turns the tables against them. Reporter Roger Nixon continues to investigate Lex's car accident and begins to close in on Clark's secret. Also, Lana becomes more distant when Aunt Nell announces her plans to sell her florist shop. Written by Anonymous
While in the woods of Smallville searching for ores in an excursion of the school, Clark Kent saves the troubled teenager Eric Summers (Shawn Ashmore) from a fatal accident near a waterfall. However, a lightning strike them both and transfer the Clark's powers to Eric. Eric changes his personality becoming aggressive, while Clark tries to help him. Meanwhile, Lex Luthor is betrayed by his girlfriend Victoria Hardwick.
"Leech" is certainly the best episode of "Smallville" up to now. The original story, with Clark Kent "releasing the world from his shoulder", acting like a normal person, but keeping his strong personality and character, is remarkable. In the end, an important moral lesson about human character and role of the parents to build the personality of a son (or a daughter). My vote is ten.
Title (Brazil): "Sanguessuga" ("Leech")