Marionette lines can develop for several reasons, including volume loss, changes in skin elasticity, and the natural way your facial tissues shift over time. The best treatment depends on what's causing the lines and how deep they are. For deeper marionette lines, dermal fillers may help restore lost volume and soften the folds. If skin laxity is contributing, treatments that stimulate collagen production, such as certain laser or radiofrequency procedures, may also help improve skin firmness and texture. A good skincare routine with sunscreen and a retinoid, if appropriate for your skin, can help improve fine lines over time. I wouldn't automatically recommend placing filler directly into the lines without assessing the surrounding areas, particularly the chin and lower face, since facial balance plays a big role in the final result. The goal is to soften the lines while keeping your features looking natural, not overfilled.