Normally Sun Rahu combination is not that much good for father.
If Sun Rahu combination is in 8 th place it will be bad for father. Native father health will badly be affected. Native will have no support of father. If malefic planets like Saturn Mars have any conjunction with this combination sure native father’s life under threat sometimes his father will meets accidents & have bad wound.
If Guru Mercury Venus see this combination native father can come out from this danger positions.
For Sagittarius ascendant 8 th Sun has own house. But some bad incidents can never inevitable.