In the Tamil language, there are certain verbs which do not follow the normal conjugations rules. They are called "Defective" or "Impersonal" verbs. Each verb has its own rules, but the one common theme is that the subject of the sentence is not in the nominative case (for example, instead of saying நான் "I", you might say எனக்கு "to me").
Additional online information about defective verbs:
- Thamil Paadanool by Elango Cheran pages 37-40
- Tamil Language In Context Unit 3 Grammar on Defective Verbs