Tamil nouns take on noun case endings instead of having prepositions like we do in English. Some of the noun cases are different for the pronouns than for regular nouns. In this spreadsheet, I have posted a chart based on Balasubramaniam's Tamil: A Foundation Course (1995, p88). There are two columns for the genitive case, just as there are in the original. I am not sure what the reason for that is, but am trying to present the information in tact.
Keep in mind that these are pure Tamil forms and are not always used in spoken Tamil. When I have more complete information on the spoken forms, I will create another spreadsheet for comparison.