The characters are a mix of sci-fi archetypes and Hindu deities.
If you want a physical copy of Gospodar svetlosti:
Zelazny writes in a poetic, sometimes archaic style to mimic the tone of ancient scriptures.
If you have managed to secure a copy (PDF or otherwise), here is a guide on how to best enjoy Zelazny's work.
Searching for "free pdf" for popular sci-fi novels is a common way for malicious actors to spread malware.
Roger Zelazny passed away in 1995, but his estate still holds the rights to his books. In most countries (including the US and EU), Lord of Light is not in the public domain. This means distributing or downloading a free PDF from an unauthorized "shadow library" site is technically a violation of copyright law.
Because the book is still under copyright, there is no legal way to download a free PDF of the full text in English. However, there may be exceptions for the Serbian translation depending on specific Serbian copyright laws, but generally, you should proceed with caution.
If you want to read Gospodar svetlosti without risking your computer's security or breaking the law, here are the "Top" recommendations: